Interesting read. Personally, long stay even in an RV park, I carry either a 5 pound or 7.5 pound 'BBQ' bottle and the few bits/pieces needed to hook into the propane system. Even though the MH's tank is 'full' I'll draw off of these as I can just toss the 'empty' in the back of the Jeep and get it filled. While 'off line,' the main tank goes on for heat, water, etc. The small bottle will/can empty in less than a week, temperature dependent. The 7.5 takes a heck of a longer time; but HEAVY as all heck (full) to lug around.
As for 'under compartment' heat, if the unit is warm, they will stay that way .. BUT the water storage does take some thinking/planning. Going to be REALLY COLD, then roll up the hose and work off of internal water tank (radiant heat will keep that ok). Hose comes 'inside' to keep same from freezing; then back out for refills.