We had a Tempurpedic for years and I LOVED it! We had it for 8-9 years and when we camped, the mattress in our TT was awful. I was on Walmart's website and saw their Gel Memory Foam mattress was on sale for $180 and figured I couldn't go wrong at that price. Ordered it and had it shipped to the campground. It arrived in a box 2 days later. We unfurled it and I slept like a baby that night.
About a year later, our Tempurpedic started getting "lumpy" and needed to be replaced. I ordered the California King size of the Gel mattress and it has been extraordinary.
When we sold our TT, the mattress went with it, but the day we purchased our fifth wheel, I ordered another mattress from Walmart. It was here at the house awaiting the delivery of the 5'er.
This is the one we have and it is as comfortable or maybe more comfortable than our Temperpedic because it doesn't get hot...ours did.
Spa Sensations Gel Foam mattress