Rather than heating the air (or, as in the case of a radiant catalytic heater, the outside of the tank), why not directly heat the water in the tank instead?
Pull water out of your fresh water tank, circulate it through your hot water heater, and drain it back into your tank. Much more efficient use of propane. A side benefit to the way I did my hot water recirculation (so I get instant hot water in the shower reducing water waste) too.
As to using a catalytic heater for personal comfort, I love mine. But, it is an Olympian product, not the Buddy heater (which I don't like at all).
In regards to enclosing and insulating the underbelly of your trailer, here are some thoughts:
Advantage (to being enclosed and insulated):
- Warmer
- Road spray (mostly) stays out
- "Less" issue with water lines freezing
- Quieter
Disadvantage (to being enclosed and insulated):
- Initial cost and effort
- It's hard to perfectly seal out mice.
- Water will find a way in and ruin your insulation unless you take efforts to mitigate the damage (i.e.; insulation supported by the floor and/or closed cell insulation).
- When you have a water leak, not only might your insulation be ruined, but it's a PIA to get to repair the leak or do other things down there.
- Even insulated, you will still need to force some heat down there. Easiest way is to simply use a fan to force some cabin heat into the area. So I am sorry to say that, if you go this route, you will have to learn to dress like a Hawaiian in your trailer in the winter. No more parkas inside for you. So sad :C
