There's a pretty good forum at
CPAPtalk.com with a lot of technical expertise. It isn't a very friendly place, but you can dart in with questions and then dart back out.
Since the CPAP is really a lifetime commitment, you might want to consider just buying your device outright. The functionality and fit of the masks is such a personal decision, but the service from the equipment providers isn't great at all. The providers work for their insurance clients, not for you.
Just like with eyeglasses, you have the right to call your doctor's office to get your prescription. Once you have that, you can upload it to
https://www.cpap.com/ and buy your own equipment. Depending on your insurance co-pays, you'll probably save in the long run by buying your own device.
As far as running it in your RV, you have a few options if you aren't already hooked up to shore power. You can get the 12V adapter for the CPAP and just plug it into a 12V outlet if you have one at your bedside. If you don't have an outlet, you can probably pay a mobile tech to install one pretty cheaply.
You can also run a small dedicated inverter from your batteries to your bedroom, but the small inverters don't typically work well with the needs of the CPAP device, especially the humidifier.
If you spend a lot of time in your RV, it's worth it to invest in your power system. You can upgrade to four 6v batteries, add solar panels (a great investment!)), and install a large enough inverter to power your televisions, coffee maker, etc. (and of course the CPAP at night).
It all depends on how much time you spend in your RV and your budget.
Also, if you travel a lot, make sure you have access to your prescription. Save it to your Google Drive or someplace where you can access it from anywhere. It stinks to be on the road and have something go wrong with your device and not be able to replace it without the prescription. If you have the prescription though, you can walk into a CPAP retailer and explain your situation and see if they have an older refurbished device that they can sell you cheaply.
Good luck.