Ray & Debbie,
Your question was about will it work, not the best deal to be found. (See, I was paying attention)
I have read somewhere on this forum that memory foam gets firmer as the ambient temperatures get lower, which is true. House temps stay relatively stable which works good for memory foam, I've got a posturepedic and really like it. However in my TD I chose to go with a foam mattress that had a combination of layers of foam none of which were memory foam, because of the temperatures issue. Memory foam softens as heat from your body transfers into it, in a cold teardrop that might take a long time and could might possibly lead to a slight hypothermia experience. If you cover the memory foam with something like a sleeping bag, the thermal transfer won't occur so the foam stays firm, but you stay warm. Just my thoughts, but since I didn't put memory foam in my TD, we need input from someone who did and has camped in cold climates and well as warm ones.