I have a hybrid latex foam mattress that’s medium-firm and I love it. My PT suggested rolling up a towel and taping it, but rolling up a feather pillow sounds more comfortable. I just purchased a lumbar pillow off Amazon (Cooling Gel Lumbar Pillow) that I use for the same purpose. I also sleep on my side with one of those contoured knee pillows (Memory Foam Knee Pillow on Amazon).