Where is the wedding located? I agree with the 16 oz 8 yarder, especially for formal situations... and doubly so if the wedding is in Maine! You'd probably be ok to go down to 13, but I'd definitely go for 8 yds.

The feeling of "thinness" probably would come from the weight of the material, methinks. It's less substantial, inch for inch. The yardage would affect how heavy the kilt is in toto, and the swing, but it wouldn't really affect that feel.