Kevin,

I have thought about the same and having discussed this with a few certified kilt snobs here is the conclusion I came to.

A pith helmet, paired with a khaki "safari" shirt, and khaki hose from What Price glory (and simple military style belt and sporran*) would be a fun and comfortable outfit for a highland games. It would be a bit costume-like in the same vein as wearing a Jacobite shirt and leather lace up boots to one. In this context I think you would look good and likely be very comfortable.

But such a rig is not for everyday wear. It is far too thearical.

Cheers

Jamie

* Handle Bar mustache not required but it would complete the ensemble