I can absolutely gaurantee that my plans will alleviate your problems of your heals digging in at night, because I suffered with the same problem for years.
In 1998 I had to have emergency surgery for perforated bowels. A week late I had my first stroke - just a light one. But 3 days later I had a major stroke. I couldn't talk, I couldn't swallow, in fact I couldn't move.
Fortunately with the aid of very good therapists I gradually regained my ability to talk and swallow again plus a limited amount of movement.
But I am confined to my wheelchair and I have to sleep on my back. I'm sure you know what that means. My heals dug into the bed and it was difficult to get relief.
My daughter made me a unit that is simple to make that has completely eased my painful nights.
I will send you the plans for this unique gadget for just $10.00.