In a week at those temps keeping the ******s toasty you may kill a full bottle. I know my wife and I did in ~ 5 days and 8500 in snow.. Ran out of gas. Agree 2 days possibly 3 if you have a nearly new battery is all you can expect.
If your going to do much of that swap the lights for LED bulbs. And consider the soalr pannel / generator or even a spare battery that you cna charge while driving arround.
Great park! We will be south of you down at Pagosa Sprinngs wiht a full hook up on the river next week
... Did our popup time now its time to enjoy a hard sided trailer ( thrid trip in it)..