Hi Bumpy,
Installing the heat strip is pretty low tech for someone who does DIY. Cost for materials is a bit more than a stand alone heater at around $70.00. Time required is well under 20 minutes.
I've separated out the control for the furnace with a second thermostat so I can run the heat strip--and if it gets too cool the propane furnace will cut in.
That said, my RV came with the heat strip already in place--and I would rather have had a heat pump. If the air conditioner fails I'll probably upgrade it to a heat pump.