I use a $17 vornado heater 750 watt. bed, bath, beyond, 20% coupon.
Small fits in cabinet. 750 watt is about 6 amps.
We set it at 1/2 and it gives a gentle waft of warm air quietly.
of course it's a while since we used it ( AZ) , but it kept us happy at temps down to 26ºF with a high of 42º
we are paying for electricity at the campground, so might as well use it vs propane.
Mike
ps "Hydro" is Canuck for Electric Service.