I have been researching this for a while now. I have two issues, camping and then backpacking.
camping: The battery packs that you jump cars will work, as well as items like the Powerdome EX. You can use a marine battery, but they are very heavy. Most manufactures offer a battery pack that will go with your machine.
Backpacking: I have no freakin idea. The battery packs would work for a short trip, but that's still 4-6 pounds depending on your device.
A lot of it depends on your pressure as well. The lower the pressure, the less juice it needs. I have some charts and such for resmed machines, if you want to post it, or PM me, I'll send you the ones that cover your machine