How Long will 2 Gas Tanks Last?

I know this is a tough question. Let's assume it's 40 degrees and I only go in and out of my camper very occasionally during camping in Dallas. How long will my LP tanks last me if I run the heater? (assuming I use it for heater only)?

Agree. The furnace is a LPG and electric hog, but your battery is the deciding factor. If you are staying in an area that prohibits generators or you don't have a generator there is a trick to keep you going for more than 2-3 days (the max your battery will last).

First, look at this FAQ. Scroll about 2/3 of the way down to the colorful red/yellow/green chart. http://www.windsun.com/Batteries/Battery_FAQ.htm
You don't want to take a lead-acid battery below 30%, which is 11.75 volts (after at least 3 hours of no loads). 50% is 12.06 volts. So once you get somewhere between those two voltages, probably in the 2-3 day range, face your tow vehicle towards the pod, hook up the two batteries with good jumper cables and run the engine for 30-45 minutes. After resting again you should see the voltage jump up to around the 80% mark (12.42 volts). Do it again every 2 days or so and you'll have enough power to get you through. Once you get home make sure you hook the pod up to your house to charge the battery back to 100%. Don't try to get above 80% in the field. Lead-acid batteries accept a lot of amps between 30-80%, but it takes many hours to go the rest of the way. It would be a waste of gas and time.

Don't forget the "hot water method" for keeping tabs on your propane supply during your trip. One cup of hot water, poured slowly down the side of the tank in one spot from the top shoulder. Wait 10 seconds then feel with your fingers - the tank will still be hot above the level of the liquid propane, and cool below it. If you do this on a regular basis you'll get a good feel for how much propane you use during cold and warm weather trips.

I concur with the results of the previous threads.  I installed dual tanks with an automatic switching regulator.  It allowed me to haul the empty tank to get filled without having to shut off the heat in the Pod.  I have found that the Pod was insulated enough that I didn't have to keep the furnace running all night at room temp...I turned the furnace down and used down quilts on the beds. However, even with dual batteries and dual tanks, I never was able to go a full week without having to recharge the batteries or refill the tanks (with Fall temps).

Just a "seat of the pants" estimate here. I have a single 20 Lb tank and ran the furnace for two days and nights camping in 40 deg weather last fall with the thermostat set at 55- 60 deg. Since then, I have run it often in 10 to 30 deg weather during storage while making interior mods. I would estimate that it has run the equivalent of 4 days total set at 55 to 60 deg. This is a lot more than I expected, although the tank is quite low now. Camper was plugged in the whole time. I doubt that the battery would be good for much more than an overnight (depending on how often the furnace runs of course).