I made one kilt wherein I incorporated my earlier thoughts only to discover that I really don't like the lowrider style at all for my physique. Even a hint of a "dun-lop", especially when combined with a larger rear (you just can't beat genes" throws the hip riders off both in the flow of how the kilt lies and in the length in the back. This is why I now far prefer the higher waist as in my Kidders, both the Black Watch and canvas.
My impression had been that the X-Kilt was for a front flap that didn't extend from hip to hip. Guess that could be adjusted considerably, but wouldn't the front panel require some vertical darts to span the front from the front of one hip to the other and still lie properly?