Shrinking a kilt isn't actually too difficult. If it were me, I'd go for it in a second.

Having said that, if you've never made or altered a kilt, you might want to give it some thought... Losing 10+ inches in a kilt turns out to be quite a lot of fabric. You'll have to redo the inverted pleat and reshape the inner apron, as well as moving the buckles. On top of that, there's the internal construction that'll need to be adjusted.

Not a difficult prospect, but not one for someone who's never delved into kilt construction. Also: sewing machine expertise = irrelevant in kilt construction. Needle and thread =