Long underwear with legs cut off can be a good option, or even long combi's with arms and legs cut off. There is often a better selection in long stuff. The trick is chosing layers that can nest comfortably within one another. As a rule I like to be able to wear everything I bring all at once, for the climate extreme of that month. So I try to avoid two skin layers. Better if one is snug and the other less so. Also best to avoid too many bottoms with low waists. Higher waists with wide elastics or draw bands is a good feature. Combi's are also good. If you could find a long enough undershirt that might be a good way to go commando, or regimental if your into kilts.