Ron, here is what I did, since I use my camper year round. I installed a separate outlet in my trailer ( I installed it the slideroom ), and ran regular solid core house wire to it. That wire comes out the bottom of the slideroom floor ( where other factory wiring was already coming thru ). On the end of that wire, I installed a good quality male "replacement end" for an extension cord. While underway traveling, I plug a dummy female end on it, and give it a wrap of duct tape to keep it clean.
Once set up at camp, I run a 12 gauge extension cord from there to campground pedestal, and use the 30A or the the 20A outlet and breaker there. Now I have a dedicated circuit to run my electric heaters. I prefer to run these small heaters on their lower setting, so when I need a lot of heat, I use two of them on low. Each pulls about 6 amps on low. These two heaters will generally provide all the heat I need, and most of the time, I only need one of them running on low ( but my trailer is small at only 19 feet ).
Set up this way, the rest of the trailer can run off the camper's 30A power panel.
Hope this helps.
ps, just to make it clear, when using the 30A outlet at the CG pedestal, I use a dogbone adapter to get down from the 30A outlet to the 15A extension cord end.