Pam,
Regarding CPAP: to get an idea of the power usage
check this link. On the features tab scroll down to "Machine Pressure and Battery Options and Performance" look up the CPAP machine on the drop down menu etc.
That will give you how many hours that battery pack will last with that CPAP. This is without using the humidifier. I don't need it during warm weather anyway. You can charge the battery with the provided AC charger and a small inverter
like this pocket inverter while driving the truck.
You can find a variety of battery pack sizes
here. I use the Powerstream PST-BP200-HR22 which uses the largest battery they offer with that battery pack.
I hope this will get you started.
Chris and Pat
2023 Ram 3500 Limited, Cummins, Aisin, dually, Auto Flex Rear Air Ride Suspension
2022 Grand Design Reflection 303RLS
2024 Winnebago Minnie 2327TB