If the circuit can run a hair dryer at 1000-1500 watts, it can run a space heater. Maybe not much else at the same time, but it will work. I do it all the time when the trailer is not used much, just to keep the moisture out.
DO get a the heaviest gauge extension cord you can find, and as short as will work. DON'T leave it coiled up with one loop over the other, that holds in heat (not likely a problem in the winter.) DO get
THIS TYPE of adapter, which is much sturdier than the short straight plug in versions.
Explain to your friends that the camper only pulls as much current as it needs. Just because there is a 30 amp supply does not mean it will use 30 amps. Current is a draw on demand, not a constant supply. Voltage is the constant supply, so the current can get there.
FYI--to get the max current you are pulling, divide the watt rating on the appliance by 120 volts. Your heater at 750 watts will pull 750/120 = 6.25 amps.
Many items have an amp rating stamped on them. Add up all the amps you will use at the same time.
Your RV has a 30 amp supply so you can run a bunch of stuff at once, INCLUDING the air conditioner, which pulls the most on startup. Most everything else can run just fine on the 15-20 amp supply.
The worst thing that will happen is you trip a breaker.
