Stomach sleeping is not recommended, but I sleep on my stomach too (and have a back problem), and the best result I got came from advice on this forum and that is to buy a firm tight top mattress then customize it with toppers. I was very skeptical, but I did this, and am thrilled with my bed which is very comfy for me. I have both support from the firm mattress and comfort from the topper this way. I had to play around with different arrangements of toppers but finally got it just right.
There's also the advantage that it's much cheaper to buy a new topper than to have to discard an expensive, plush mattress which starts to sag in the middle.
