Propane heaters that are built into the RV are very inefficient. That is why you are burning through propane. As for solar, to be close to self sufficient with solar based on your rig, will require at least 700 watts.
We have total of 1000 watts, do not need to elevate. I average about 29 Amp hours from 10am to 4pm. 660 Amp hours of battery capacity. This will get my batteries back to float mode.
We recently installed a Mr Heater Big Buddy. Used 3 gals of propane in 8 days. Used this to take the chill off evening and mornings. This raise the temperature from 59 to 67 degrees in 1.5 hours (early mornings). My question is what is it you really want to do? Are you trying to limit cost or just trying to limit your carbon footprint?
