By the way, if you look at my profile pic, the shirt I'm wearing is a super- stretchy, surfing type shirt. It's really thin material, made completely of spandex or lycra or something, and is quite comfortable. One of those might help you.
The only problem with them is that, while they're quite long (or can be, if you pull them down around your legs which helps to flatten you out) they do tend to ride up.
Perhaps some sort of unitard would do you good.