What tent is it?
I am now taking my philips CPAP away for two nights camping on a regular basis. I use a 12v cigarette/accessory socket lead direct from philips(£25), a clip on cigarette socket adapter (£5) and a 10Ah 12v agm lead acid battery(£20-30) and manage two nights no problem. Much cheaper than the Lithium packs. If I am going away for longer or in the car or van I have a bigger battery I take.
It’s a Cinch! 4 man with the Solar panel kit, sun reflector and front canopy. It’s a popup, but a high quality, double skinned one and the largest on the market I know of. It’s not super fancy, but it’s quick and easy which is what we like.
I’ll consider your option, sounds brilliant. What charger do you use?