I remembered Jeff talking about his Mr. Heater Buddy last year commenting that it works great while boondocking (no electricity).
We are going on a 4-day camp out next week without hookups and I had always recharged my batteries with the solar and never worried about it. Now looking at the current forecast, we are supposed to have rain all 4 days. That means no recharging. 
With my Victron battery monitor I already know my furnace blower is a major battery hog. With my dual Group 29 batteries, during the summer (no furnace) I can easily go 24 hours and only consume <10% of the batteries. Therefore in 4 days I would be down 40%. However, in the winter I have the furnace blower going and in 24 hours on a cold day/night 30-40 degrees I can consume 25%.
This looks like the perfect solution.
I see there is a smaller version MH4B with 3800 BTU. It sits on the bottle so very compact.
http://www.amazon.com/Mr-Heate...opane/dp/B001CFRF7I/
I assume the larger version you mentioned heats the area quicker if set on high (9K BTU), but consumes 2x the fuel.
I like the smaller size of this little guy and since I have the green bottle refill adapter I don't care about using many small bottles.
Anything else I should be thinking about before I pull the trigger here?