If you have plenty of material and it is lightweight then I'd advise using lots of material.

I've only been making kilts for a couple of years and my methods are not conventional, but I have only ever regretted not putting more material into a kilt.

For a 42 inch hip measurement I'd go for at least 22 inches of pleats - at the hip, that is. Maybe 24 inches or even more would be better, particularly if you have got a bit of a 'bay window' in front. Its the shape, not the measurement, that is important and although the fabric will bend to accommodate the shape beneath, it is going to look better if there is enough kilt to go round the body, even if it is hanging over fresh air. You want to look dressed, not parcelled.

The pleats are narrowed into the waist and sewn down in the conventional method, the aprons are shaped so as to be slightly wider at the lower edge - though when worn they actually hang straight, the curve of the body makes a straight apron look as though it is narrower at the bottom.

There is a large pleat folded under the apron and under apron so that it is possible to lift your foot to tie a lace without having the aprons pull apart. There is also one more large pleat folded the other way, again for ease of movement, but also for modesty - if you sit or crouch down you want the aprons to fall between your thighs. If there is enough material the under apron can be pushed backwards so that even sitting on the ground does not provide an unfortunate photo opportunity.

The large pleats are useful to get the sett lined up nicely on the apron, so the pattern is placed so it looks right.