Just to update from my Dec 10 09 questions; after much debate I installed something different from the Atwood everest series for a couple of reasons, and not to say that the Atwood has its pluses, and I do like its freatures and what you've done and inspired me to install a heater. One drawback with this heater was it was more expensive than the Atwood by 200, but Im satisfied that the extra expense is justified.
I settled on installing a Dickinson Newport fireplace marine heater (boat). It use no 12 V if needed, no fans required; simple and reliable design, it uses less propane that the Atwood (I think), all stainless steel construction; vents and draws air form the outside and you can watch the flames like a fire place.
Some of the drawbacks are; its all manual controls (no thermostat attachment like the everest); you need to light it with a match or BBQ lighter. I use a BBQ lighter without any problems. You have to follow the directions so things warm up and vent / circulate properly. It cant be connected to a thermostat; and it only has 2 heat settings; high & low ... but I'll probably only use it while awake and can crack a window if it gets too toasty. Heres a pic for refrence others in album and updated build post.