You will need to check your unit to see if the control board and thermostat will control a heat strip. If so they are pretty easy to install.
We have a heat strip on both AC units and run them on the low fan speed. Both units have their own thermostats and 3 speed fans. During the day they keep the 5er at the desired temperature without using the propane furnace. They maintain the inside temperature, when the outside temperature falls into the upper 30's. I set my propane furnace thermostat to come on if the AC heat strips can't keep up. This usually happens at night when the outside temperature drops. If we are running the ceramic heaters, they come on first, then the heat strips, then the furnace. The bedroom area seems to stay warmer than the rest of the 5er so that unit does not run much. My heat strips came from the factory with an in line fuse and overheat device, plus they are fed from the AC through its circuit beaker, so I feel safer using them. We always turn off the ceramic heaters when we are not inside the 5er. I think you will find them a great addition to take the chill out of the air in the spring and fall camping season. To me they feel like the air coming from our heat pump at home. Not warm like gas or oil heat but acceptable.