Our son just bought us a heated mattress pad for Christmas for use here at home. I put it on very low just before going to bed and it is very comfortable. I would imagine that it would be much warmer if I cranked it up all the way, but set on a low number, it works great. It has an automatic shut off after 10 hours.
Mattress heater. I'm assuming you're plugged in, cause if not you'll need a good psw inverter.
Agree. Winter travel with furnace t-stat set to 55°, the queen mattress in an extended cab-over of a TC can get pretty chilly in sub-zero temps. Memory foam topper becomes a concrete slab. A 10-15 minute warm-up with a mattress pad warmer makes everything soft and cozy for the night.
Quality 12v warmers are available at Electowarmth. They used to offer sizes in king, queen, double, etc. I purchased a queen size back in 04 from Backwoods Solar (same product/lower price) and it lasted 8 years. The pads were pinned to the mattress, not form fitted. Now, the manufacturer makes only one size, 36"x60". Based on experience, too many pins to deal with on larger mattresses, ie., tears in the middle of the mattress cover and possible overlapping of pad(s). Now, I use a 120v Sunbeam, form fitted, purchased at Wally World. You'll need a psw for off grid use. The controls are sensitive.