In my experience, I've found heat strips in the A/C pretty much worthless, mainly because they are trying to blast warm air down on you, which tends not to work well, especially with the heat exchanger nearby.
I like using the on board propane heater because on some models, it will blow warm air on the tanks, which helps in light freezes. However, above freezing, I like a good old fashioned fan-forced electric heater like a Vornado, which doesn't make hot air, but lots of warm air, evenly heating the rig.
Barring that, I have been tempted to use a Big Buddy heater just as a way to supplement the furnace, so the furnace only has to come on in the wee hours of the morning, saving battery. Of course the answer to this are some solar panels long term.