jdadoug-- I wonder if you are refering to the Perfect Harmony Mattress Topper sold at Camping World. I camped my way home after picking up my new TT and spent 6 nights on the OEM mattress. It got pretty hard by the end of the trip. Thinking of my wife (always) I thought we would like something a little more comfortable. I purchased the Perfect Harmony topper and have been very happy with it. It is very comfortable and the combination with the original mattress makes for one very good sleeping platform. It will "breathe" more than the orignial mattress and feels cooler. I bought the short queen and regular queen sheets fit on it without any problem. It is 2" of memory foam topped with 2" of "Angel Soft" material. It can be taken apart to wash the "Angel Soft" top as needed.
The mattress heater will be of no use. I bought an electric blanket for some late fall camping in cold weather. Very satisfied with the product. It is more expensive than just the foam topper but the 2" of Angel Soft is quite comfortable.
Just my opinion and my wife liked it also.