You actually don't even need more than one line of basting stitches but they help.

Here's my suggestion based on how I do the same thing. This is an abridged version of a chapter from "The Art of Contemporary Kiltmaking"

Even though I have big, tall lay-out tables in my shop to lessen the dreaded back strain I don't think guys are built for that kind of work. I use much the same technique as you describe when basting, but I'm doing pleats from scratch so I need to pay careful attention to where each pleat is folded and the distance of the pleat reveal.

When I stitch the Fell on SWK's and others like them, I change how I do it and opt for comfort.

You should have already determined where the bottom of the Fell should be by putting on the kilt and marking where the crest of your butt is.
While you still have the kilt on, have someone measure across the back of your butt at the bottom of the Fell from apron edge to apron edge.
Then lay out the kilt on your table and note where the bottom of the Fell falls corresponding to some horizontal line of the Tartan pattern. This is where you will baste the pleats to hold the reveal constant while you stitch.

When laying the kilt on your table you will find that the waistband and Fell area can be flat on the table causing the pleats to splay or the pleats can be flat and parallel causing the waistband to bunch up. One or the other, but not both because of the shaping of the kilt. What you want are the pleats to be flat and parallel, so I have found it helpful to roll up a bath towel and place it behind and underneath the waistband to hold it up in the air as I work the pleats nice and flat a perfectly parallel. I also find it helpful to use my steam iron to shoot jets of steam at the fabric to soften the fabric and help it lay down. (don't try to iron the pleats, just shoot some steam at them from a couple of inches away.)

The next step, basting the Fell, will require a yardstick or straight edge and your tape measure.
Use the yard stick to insure the hem is straight. I have some large aluminum yardsticks I use for this step and lay them on top of the hem and pull and tug the pleats until the hem is aligned with the yardstick. (If you align the hem straight and work the pleats straight and flat you will notice that the line at the bottom of the Fell line is also straight and parallel to the hem.)
Now move the yardstick up and place it just above the line you chose as the bottom of the Fell. (Instead of saying "Bottom of the Fell" all the time, I use the term "Steeking Line". On a Traditional, hand-sewn kilt the Steeking line is a line of stitches to support the pleats when you cut away the back of them in the Fell area, but for our purposes here I'll use it in the Contemporary Kiltmakers fashion to denote the line at the bottom of the Fell.)

Using the measurement taken of the pleated area at the Steeking line, divide that measurement by the number of pleats. This will give you the amount of reveal of each pleat. Now you are going to baste the pleats to hold them in position while you stitch the Fell.

Basting the Steeking Line is very important and must be done carefully and accurately. The yardstick is used to prevent cumulative error. So align the "0" mark of the yardstick with the edge of the under apron (at your right looking from the hem to the waistband) and hold it there with a weight of some kind.
Then begin basting from the right to the left. I use a clove hitch when basting the Steeking line because I find it holds firm and won't slip as you move the kilt around later. but any good firm stitch will work.
Adjust the width of the pleat reveal using the yardstick and stitch the second pleat to the first. Then pull the thread over to the third pleat and put in another basting stitch. Pull the thread between the pleats tight and keep the reveal the same by using the yardstick. (For example, if your reveal is 1" then the edge of the first pleat is at "0", the edge of the second pleat will be at "2" on the yardstick and the third at "3". and so on.) I try to put my Steeking line bastings right on the edge of each pleat and pull the thread between the pleats nice and tight as I go.

The basting is done below the Steeking line and I simply use one of the horizontal lines of the Tartan pattern to keep everything properly aligned.

When you are done basting all the pleats, the measurement on your yardstick at the last pleat should equal the measurement you took around the back of the pleats while you were wearing the kilt.

Now you can take the kilt off the table and nothing will move around. You can find a comfortable chair, ball the kilt up or roll it up and not worry that your measurements will creep on you.

When you start the sewing of the Fell itself you start on the left side or opposite end from the way you did the basting. Simply pull the waistband till the Fell area is nice and tight and start your stitching.

It is very important to pay attention to how you do the actual stitch. If you are right handed the waistband is away from you and the needle is in your right hand if left handed I find it helpful to reverse that and place the waistband near my stomach and the hem hanging over my knees.

Begin stitching by knotting just one of the two lengths of thread from your needle and starting the needle under the first pleat to hide the knot.

I'm going to use some terms here so I think I should define them. You will be working on two pleats at a time. Sewing the edge of one to the flat of another with the reveal exposed on the second pleat. So I'm going to call one pleat the top pleat and the other the bottom pleat. The top pleat is the one you are stitching just at the edge and the bottom pleat is the one you are stitching the top one too.

With the waistband already sewn on you can pull the Fell area tight and the pleats should lay down straight. When you sew, you just need to pay attention to the alignment of the horizontal lines of the Tartan to insure that your stitches don't pull and offset that alignment.
Stick the needle into the bottom pleat just off the edge of the top pleat. Then bring the needle up through the bottom and top both so that the stitch just catches a couple of yarns at the edge of the top pleat. Then move up slightly and go back down into the bottom pleat. Your first stitch is done.
Now continue, ad nauseum, till you reach the waistband.

Get ready to rip out everything you have just done, because if you have never done this before you will find that the horizontal lines of the Tartan will have shifted as you pull the stitches tight. This is normal. It will take some practice till you can judge how much to offset the top pleat from the bottom to take into account the tension of the stitches.
Now I'm kinda clumsy with hand stitching and I don't think it took me more than two or three years to get the hang of how much to offset the Tartan lines so my stitches will pull them back into alignment. Most people will get the hang of it after ripping out only two or three times.

The goal is to make little tiny stitches that are invisible, to get the tension of each stitch the same to align the Tartan pattern, and to make the whole thing strong enough to withstand the stress of you moving and sitting in the kilt.

After you stitch one pleat, I find it helpful to shake out the kilt to get everything nice and straight again. If you want shoot a couple of more jets of steam at the Fell this will help the back or underside of the pleat to lay straight and not bunch up against your back when you have the kilt on.

Then start again. Stick the needle down into the bottom pleat just off the edge of the top one. Catch just a couple of yarns then come up catching a couple of yarns of the edge of the top pleat. Pull it tight and check the alignment of the Tartan pattern. What could be simpler?

I find a nice comfortable straight backed chair to be the best. I also get as much light on my work area as I can. I have big fat guy fingers so I use as long a needle as I can find and I use a ring thimble. Look at Barb's post about her leather thimble and use one like that if you can find one. Don't try hand stitching without a thimble. Oh I know, it's not manly to think of yourself sitting down with a needle, thread, thimble and sewing. Too much like your granny or mom for many men, but once you get into it, it is a very relaxing way to spend a couple of evenings in front of the TV. And the bragging rights you get from doing it yourself are worth anything.

Good luck and I hope this helped.