My small ceramic heater is 1500 watts on high speed, so that's about 12.5 amps (volts divided by watts) Im sure there is an initial surge to factor in.. I should probably put my watt meter on it to confirm - anyway as long as the circuit you are plugging into is rated for 15 amps or more, you should be fine with a heater that is rated similarly with your generator providing the juice. You didn't mention which honda generator you are using... if it's the 2000 watt model, you are producing enough power to run *my* heater + 500 watts before it's totally maxed.
If you let us know exactly what generator and heater (with specs on current draw), we can tell you 100%, but I think you are fine as long as you aren't running a lot more than just the heater and it is rated similar to mine.
Will the campers electrical system handle that load? Absolutely. It handles your microwave oven and AC right? (not sure if you have a microwave, but I know your camper came with them originally), just don't run them all at the same time, which would be kind of funny in that example anyway.
2016 27BHS Elite
2012 F-150 EcoBoost / Max Tow