As a fellow bony side sleeper, I considered Exped, which are heavy, Big Agnes, and when the recent released NeoAir came out I finally bit - the Neo may be expensive but it's less expensive than the Exped Downmat I was considering.

Prior to this purchase I began sleeping in a hammock. Since the NeoAir works well for me in the hammock and on the ground, I consider myself adequately prepared - the hammock is still more comfortable than sleeping on the ground, and when unable to set up the hammock, I have 2.5" of inflatable mattress and a thin foam pad to make it easier to tolerate a night on the ground. I know I'll be comfortable to 30F and above, as this is what I experienced; I think it will go lower if I need it to, with the foam pad.