[ShrimpBurrito]

I haven't read the threads Bill referenced above, but I know that an easy but expensive route to go is to buy a portable CPAP unit with an auxiliary battery. That will last all night for sure.

I have camped with someone in our TM who used a CPAP -- I hooked it up to a small 150 watt inverter and plugged it into the cigarette socket by the fridge. I think it only draws 60-70 watts, maybe a bit less. At 12v, that's about 5 amps. If you use it 8 hrs/night, that's 40 Ah. A large 12v deep cycle battery (Group 27?) would last throughout the night, even with moderate usage of the TM appliances (except the furnace), but wouldn't have much energy left by morning. You'd definitely need to fully recharge every day.

If you added a second battery, you could easily go without a charge for 2 days, and maybe 3. Again, assuming moderate use of TM appliances, and not the furnace.

Dave