When I am making my kilts - which are, admittedly to a different style but the front is going to be the same - ish on all kilts, I make the aprons so they fall vertically when I sit down.

This is a combination of large under apron pleats and placing the edges of the apron in the centre of the thigh, so they slide down the inner curve rather than lie over the top.

This means that the area of pleats actually wraps around the hips - if you aproximate the shape to a box you have visible pleats right around three sides and over the edges of the fourth.

I always shape the left edge of the apron and the right edge of the inner apron by two inches - those are the edges within the kilt, but leave the ends straight. I make a two inch fold at the edge of the apron and press it so it tapers to nothing at the lower edge, because otherwise it looks as though the apron narrows.

Behind the shaping fold is the under apron pleat - usually I put all the leftover material into it, but it is nominally half the apron width, so there are six layers of fabric in the front of the kilt. That will allow you to move, even kick up your heels without too much danger of a can-can reveal.

(The early exponents of the can-can used to dance on tables with no drawers)