I don't think you need to be concerned about their availability. Since the road is not closed and is traveled by quite a few different kinds of vehicles, even relatively early in the year, there will be gas available at increments less distant than 450 miles or whatever range you end up having. Likewise your propane supply should be good for at least a few days, probably at least a week with furnace usage during the nights, and propane will be available at the larger cities at the least which are not weeks apart.
You likely won't need propane during the day when driving as I suspect the Ford dash heater will keep the interior reasonably warm for the little 19' Cruise America class C that you apparently will have. (Cute little rigs, too).
I suspect water will be the consumable that needs the most conservation. Disposable plates and cutlery and limited showering will help a lot with that.
