Hi,
If you are just camping for a couple of nights, it would be a hassle to run the extra power cord, and you really do have 30 amps inside the RV anyway. You can plug in the heater inside. I would not recommend a ceramic heater - unless you already have one. Their up front cost is much more than a standard heater, yet I do not like that they put out very "hot" air, not a comfortable 95- 105F air temp. This can ignight things!
I have a cheap Wal Mart $20 heater that also has a fan to bring in cool air in the summer. It is quiet, check it before buying. I have bought some really noisy fans and heaters in the past. Just look for a outlet at the store, plug it in and turn on the fan part.
While camping, when you would normally run the electric coffee pot or microwave, then shut off the heater for a few minutes. Really is that simple.
That said, while living in my RV in Portland Oregon, and it was in the 30's, I did run a #12 heavy duty extension cord to my power post and ran it through a factory installed hole under my bed into the basement, then out the electrical feed hole to the power panel. This ran my bedroom heater, and I did not need to shut it off when making coffee. I ran two other heaters on low heat output on the 30 amp system, then this one on 1500 watts when I wanted too.
Fred.