I know you wrote this answer to another question
awhile ago, but I had to add a comment because I’m in the same situation!
Memory foam is useless for your purposes. Once it warms from your body’s heat, it collapses as if it weren’t even there.
What’s more memory foam is dangerous health hazard. It off gasses some very toxic chemicals. It’s comprised of 61 chemicals, many of which are toxic and a few are carcinogenic.
To cushion the surface of a mattress, use a latex topper. Latex is all natural and chemical free. Made from the sap of the rubber tree, it is extremely resilient and extraordinarily comfortable.
And, unlike memory foam, it will last for many years.
Here is the link to the latex toppers.
The EverEden 2″ soft talalay latex topper is the most popular and does a fine job of transforming a too firm mattress into something very comfortable.
Latex Mattress Topper
My wife and I use that same topper on our mattress, which is a Natura Greenspring Liberty in Ultra Plush…which has no memory foam.
Delivery is Free and there’s NO SALES TAX