I just added a heat strip to my a/c unit myself and it screwed right in. I was told by Dometic that it's a 1500w heater. Heartland was also "nice enough" to have already run the 7 (?) wire thermostat wire for me ... the units without the heat strip only need 6 (I think). Either way, the wire was there and not used until I came along. It came with a new thermostat (it has a heat strip switch setting on it).
I like it and, so far, it's worked well for us. I don't have to worry about my little kids touching it or knocking it over and it doesn't take up floor space. However, I use it to keep the chill away at night when we're all covered with blankets. If it's really cold outside at night, we'll use the furnace to heat the rig. I also like the quiteness of it since you only hear the a/c fan blowing - which we have on most of the time anyway. The furnace fan wakes me up almost every time it cycles on and off.
BTW: I bought and installed it myself because I wanted to save on my propane costs, the other stuff was just a bonus. Also, if I remember correctly, it cost me around $130 from PPL.