I use an bypap machine too. I just purchased a 12 volt cigarette lighter
power supply for it. I plan to plug it into a power outlet in the closet in front of my 5th wheel next to the bed. I also pulled down the setup instructions for my bypap model and I will tun off the tank heater and the hose heater. BTW those instruction to turn off heater also came with my last new hose or head set (can't remember which)that I received. I measured the amount of current draw with heaters off and I believe it should run over night from the 5th wheel batteries. I do have 2 @ 12 volt group 27 batteries hooked in parallel which is a total of 178ah. The bypap runs good off the power supply but I have NOT tested it all over night yet. But I do believe it will work out. It seemed like a cheaper solution then buying a dedicated battery backup. I still plan to come up with a solar setup to recharge my hose batteries. I do also have an inverter generator to recharge batteries when needed.