First a little lesson. The 'converter' is really a converter/power center. It converts 120vac shore/generator power to 12vdc AND distributes 120v & 12v power to the whole RV as well as changes the battery(s).
An inverter runs off the battery(s) and inverts 12vdc to 120vac to run ac appliances.
Now, as for running a couple of electric heaters, it won't hurt the converter. You will have to be sure not to overload the breakers in the RV.
Salem 29RKSS Pushing a 2500 Mega-Cab CTD!
Gotta go campin!