Everyone here is a wealth of information (and experience)! Thanks!
Judging from everybody's input I think the 1500 w 120 v ceramic heater will probably suffice for the majority of my camping needs (30 degrees and higher). That's good to know since I'm not very fond of using gas/propane heating while I'm sleeping in a TT. Have to admit I'm pretty surprised to hear the OEM heater puts out 6 times the heat of a 1500 w ceramic (ref subcamper).
A few folks mentioned keeping their holding tanks warm (from freezing??) by using an OEM propane heater. How so?
