I've got the two side seams done, the pockets in, and one side of the pleats sewn down.

here's the steps of putting in the side seam and pocket. First the two pieces are trimmed appropriately; for a thick fabric like the duck cloth, you need about 3/4 inch seam allowance to do a french seam. Put the wrong sides together, at the edges:

You can also see that i've undone the hem for a couple inches before the seam. there's no need to have the hem in the seam, so we'll trim it out before I redo the hem.
I sewed a seam from the hem to the fell (which will be the bottom of my pocket opening), with a 1/4 seam allowance. Press that flat, turn the fabric right sides together, and sew another 1/4 seam, and you end up with this:


here's the pattern I used for the pocket bags:

the two inch extension on the lower right of the piece is what's used to attach it to the flap. I've got the entrance to the pocket at the bottom of the pleat. That means that the side of the pocket that's closest to the wearer's body is shifted an inch (in my case; in general, it's the difference between the pleat depth, and the pleat reveal) towards the center, compared to the part that's farther away. Since i used the same pattern to make both halves of the bag, the seam at the far opening isn't on edge of the pocket. I put it back there by putting in a pleat at the top of the bag, when it's sewn to the top of the kilt. Here's the bag sewn shut; again it's a french seam, this time with a 1/8" seam (well 3 mm, since that's what I've got marked on my Swedish sewing machine).

This is the inside of the kilt. The part to the right (which is the overapron side) has the pleats sewn down; the side to the left only has the first two or four done.