I'm not sure if this will solve your issue, but I use these for layering ALL THE TIME:
http://halftee.com/the-origina.....tee-3.html
I usually want the coverage on my neck and/or arms, but I don't necessarily need it anywhere else and I hate feeling hot and bulky when I wear layers! Anyway, the reason I thought it might be helpful is because the full-length cami, for me, feels a lot more flattening--not sure if it is the extra fabric or the cut, or what--and these halftees fit me more like a really really soft sports bra. They mold to my curves just like a bra (I am wearing a regular bra under, of course) and I like the resulting layering look.
Not sure if this is helpful . . . I hope so, though