You need more shaping - and possibly more width available for walking than would be designed into most kilts - from what I have seen.

I'm not sure that a box pleated kilt would be the easiest to adapt, I'd think that knife pleats and more opportunities for tapering would be the easier way to go.

A tapered apron, quite narrow, and lots of pleats with a fairly narrow reveal at the waist but generous depth will give you the best chance of having enough expansion available to create a more or less cone shape around you rather than the more D shaped cross section of the traditional kilt.

I'd take a generous length of material and start to pleat from the centre back, then keep on pleating right around to enclose the hip joints, and make the under apron pleats deep enough so they go right to the centre front - you don't want to be short of material when getting into a car or stepping over a low obstacle.

For a good fit I think you are going to need lots of material, but it should feel great to have it all moving around you, giving you space to move without restraint.