I'm using the Philips Dreamstation with the removable humidifier.
After looking at the travel type CPAP units, and also finding there are various battery power packs available to run the machines when no mains power is available, I have decided I will ultimately go that route rather than buy a second small CPAP unit.
A power pack capable of running the Dreamstation for up to six days is available for just under $700 Au.
The lightweight CPAPs run around $1,200 Au., so I figure I'm $500 ahead on the outlay.. though there are other cheaper power packs that are lower capacity and will only run a machine for one or two nights.
My camping is by four wheel drive or motorcycle, so I will have to change how I do it a little to make sure I can take the CPAP with me.
When using the 4WD or motorbike and sidecar I will bush camp on trips because I have the room to carry the machine and the power pack, along with all my camping gear.
When doing a trip on two wheels I will have to settle for pub/motel/caravan park stays and leave the camping gear behind, but the routes will still be back roads and forest trails... it will just take a bit more map planning before each ride.
Ultimately it comes down to modifying how you do things, and what you carry on trips, to accommodate your new situation of needing to use a CPAP nightly.