I've come kind of late to this discussion, but I also have a CPAP that needs power every night. My trailer has two batteries that are used for power at night. The CPAP has a direct 12v connector and I will also use a 300 watt inverter as a backup. I have been able to go 5 nights without using my generator by charging with a solar panel during the day.
The generator I have used for the past seven years has been a 2000 watt Champion. This past summer I spent 10 days camping in 100 - 105 degree temperatures so I now have a second Champion I can combine to run my air conditioning unit. The first generator cost about $450 and the second one was $395 on eBay (factory rebuild).
The batteries on the trailer were group 24 12v which I replaced last week with two 6v batteries. All totaled this is a fair amount of equipment but it sure beats waking up to a mask sucked into your face cutting off your air.
2007 Toyota Tundra 5.7L
2015 Shadow Cruiser 225rbs