Here's an additional thought on depending on the propane heaters, to add to Michelle's comments.
If you still have the original control boards in your heaters, they sometimes will have a failure mode where they try to light the flame but it does not light. The OEM board only tries one time to get a light! If flame does not light, the blower (fan) motor will continue to run indefinitely, circulating cold air, until such time as you manually turn off the heater at the thermostat. Besides not helping to heat the coach, this failure mode will rapidly deplete your batteries.
The solution to this problem is to use Dinosaur control boards in both heaters, but of course this doesn't help you today.
Amazon.com: Dinosaur Electronics (UIB S) Small Universal Ignitor Board:...
Dinosaur Electronics Home. High quality circuit boards for RV appliances.
Since you are already paying for the 50 amp power hookup, I would strongly encourage you to try to use small thermostatically controlled heaters for your primary heat source, and save the propane heaters for backup. If you put a heater in the wet bay end (faucet end) and crank it up, the heat will travel across the top of the tanks to the other side. Our coach is plugged in to 50 amp in our driveway. It is out in the open, uncovered, and I do not winterize (with the pink stuff). We have small heaters in both ends of our wet bay, and right now, after several days of temps in the teens, our wet bay is holding at a balmy 60 degrees.
Small heaters also work well inside the coach. We have 5 of them running right now spaced out in the coach. They are presently maintaining the inside temp at about 55 degrees, but the propane heaters (set at 50 degrees on the thermostat) are coming on once in a while to help them out. We have Dinosaur boards in both propane heaters and they have never failed me........YET!
We're going down to -3 here tonight (Midland, TX), so my "no pink stuff" winter parking technique will get a very good test.
As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.