Unfortunately, outside of what was noted by John Stevens, very little is known about the uniforms or flags of the Jacobite army, so they obscure in a literal sense. Its a fair bet that some regiments did not have uniforms, and those that did probably wore red or grey coats, possibly a mix, and uniforms may have been mixed with civilian clothes. While this is something of a frustration its better to treat it as a freedom; so long as your choices aren't outrageous you can't be told they are wrong. I know Barry is very much an advocate of this approach.
Clarence's recent interpretation of Clanrickard's regiment is pretty spot on in my view;
http://leagueofaugsburg.blogspot.co.uk/ ... rl-of.html