Hi,
You need some stronger straps, and perhaps more of them!
I would suggest a Olympic Catalytic heater, some might also suggest the power vented Platinum Catalytic heater. I have to leave my roof vent open and the 6,000 Btu Olympic that I have will heat my 30' Bounder without running the furnace down to about 30F outside. Any cooler, and I would need to run the furnace a bit to blow warm air into the back area, and the basement to keep it from freezing.
Most RV's with a basement storage will also include a 2" air duct from the furnace to keep the basement above freezing, but it relies on the furnace running enough to keep the RV interior above 65F. If you can warm the fresh water tank with some hot water from the water heater, it will allow you longer showers, and prevent it from freezing as well as warm the basement.
When I was living in my RV, I bought a L5 propane instant heater rated at 5 liters per minute at 40F rise. So basically I would fill my 100 gallon fresh water tank with 95F water instead of 55F water, and my 6 gallon water heater would last 15 minute showers! The fresh water tank ended up being about 70F once full.
You could also run a hot water line from the kitchen to the fresh water tank, and just open it when you want to heat the fresh water tank, and heat it 6 gallons at a time, until your 'cold' water is say 75F. It will cool overnight, and still be warm enough for a long shower the next day.
Take along lots of propane bottles. It helps to have a 'extend a stay' so you do not need to lift each bottle into the propane storage compartment, but can run a hose to a portable bottle sitting next to the trailer - if you will be there a while.
What about 12 and 110 volt power? If you could run a 120 volt electric heater from shore power, it will offset needing so much propane. But it is not going to work if running the heater from a generator, it will just consume the fuel that much faster. If you will have shore power, a electric blanket will work well. However most electric blankets will not work from modified sine wave inverters, that is how I ruined mine.
You can run a ink jet printer from MSW inverter, but not a laser printer.
Have you considered solar power? While it might not work if you are way up north in the short winter days, it will work out great in the summer time!
SunElec.com A 400 watt system will run your RV pretty well. Otherwise you will need to run a generator about 2 hours morning and night if running a furnace a lot, and less in the summer, say 1 hour morning and night. Your RV will consume about 35 amp hours just to run the refrigerator, CO and propane detectors.
Your lights are about 1 amp hour each, until you change to LED bulbs or panels. Furnace typically is 7 amp hours.
You should also consider upgrading batteries to 4 golf cart batteries, 440 amp hour total capacity at 12 volts, and enough that running from a generator, you can charge at 35 amps per hour and not need to run the generator so much. With a 120 amp hour battery bank, the first hour charge might be at say 25 amps, but second and third hour would only be charging at about 10 - 15 amps per hour. This is why I recommend running the generator twice a day, because the first hour of charging is the highest amperage output from the charger, while hour 2 is less, and hour 3 is really slow charge - compared to hour #1.
You might also find that some "Refetix" insulation is great! I have some cut for each of my windows, and while I bought it originally to keep out light, it is also effective to keep out heat and cold. It is 3/8" thick, and sliver coated bubble wrap stuff, that is rated at R-4.
Have fun up there!
Fred.
