> My question is, everything reviewed discusses which bag is best suited for back sleepers and side sleepers, but I have yet to see anything mentioning anywhere about a bag suited for sleeping on your stomach.
One of the problems here is that many proposed solutions involve sleeping bags whose design is not suited for you. Some of the so-called quilt solutions are poorly designed as well. A bold and controversial statement perhaps, but let us consider it.
Do you use a quilt or doona at home (or even blankets)? Does this have a hood? Does it have a bit going underneath you? Nope. So what do you do when it is really cold? You pull your quilt over your head. This idea works regardless of what position you sleep in.
OK, now back to camping. Why do so many people use such strange compromises for sleeping? Things like the WM Top Bag recently reviewed here? A weird beast - part quilt and part sleeping bag, but not very good at either role.
If you want to use a sleeping bag, do so. If you want to do the hood up and roll onto your stomach, do so. Do the hood up first, THEN roll over. But don't do such silly acts as trying to do the hood up while your face is buried in it. The hood is meant to cover the back of your head, not your face. Use it as it is intended.
If you want to use a quilt, then use a QUILT! Use one which is long enough that you can do in camp just what you do at home: arrange yourself on your mat(tress) however you like and pull the quilt over you and as much of your head as you need (as several others have suggested here).
Yes, there are many strange things offered out there. Most of them are pretty weird and don't work very well. Define what you need and look for THAT.
PS: I use a quilt exactly as described, summer and winter.