Pretty exciting stuff there, Colin!

My understanding is that the kiltmaker will use the measurement you provide to set the buckle to secure in the middle hole of the strap... at least this is the way all of my trads were built. If concerned about it, you might inquire and see if they can provide longer straps.

Personally, I love the way a traditional kilt fits. I suspect you will too. I also predict that after trying it, it won't be your last.

Congrats!