Sorry I know I've posted about it before, but I wanted to take a second to pimp the best teardrop heater I've found.
If you have 110v seriously look at this little guy
https://www.amazon.com/Ontel-Handy-Heat ... 01L9UKAHM/
its only 400w, but in the limited space of an insulated teardrop, I have kept it a toasty 70 inside below freezing outside. Two speed fan, adjustable temp digital thermostat, its really slick for under $20.
We had the TD out this last weekend when it was getting into the 40s overnight and my daughter didnt pack for the weather, made for a nice place for her to hang out to keep out of the cool.
Seriously considering a second one and doing more mid winter camping.