Just a quick report, if it helps, we took our 2016 Greyhawk up to 10'000 feet last Friday. Weather is still mild here for November, night time temps dropped to about 30*F.
Our Coleman Mach 8 unit has heating strips, not a heat pump. I decided to give it a try.
Report is - it worked very well. I had no trouble keeping the inside at 72*F with just the heating strips. Sure, the unit cycled on about every 10-15 minutes...
But it worked. It'll conserve propane if you happen to be someplace where there's electric.