I got a 12v "throw" off Amazon years ago and use it all the time when we're out in the winter. It has a 45 minute timer which warms the mattress in the teardrop --- if it's really cold I might cycle it a few times during the night too.
The teardrop has two 122 ah boat batteries and 100w of...
I saw Toni Bou a few times and he did things like that. At the end of the show he used the bike to smash out all of the windows and then crushed the car nearly flat. It wasn't a Prius but some other commuter box.