Hey Herb, don't forget that as much as you want to seal up every little draft in your camper, you still need to leave a way for fresh air to enter, so you don't run out of oxygen- especially with the propane furnace running. I'm pretty fussy about leaving a vent open slightly in my trailer when the furnace is turned on. I hear of people dying in their sleep in RVs by asphyxiation quite often and none of us wants to become a statistic. A lot of people tempt fate even further and will light the oven or stove burners to keep warm. Never a good idea.

 

Just bought a carbon monoxide alarm to put in the camper.

 

A cold floor is your worst enemy. I have a rubber bed mat and that helps keep the floor warmer.

I would avoid any type of non vented (catalytic) heater. They will deplete the oxygen level to dangerous levels without tripping a CO alarm. Hopefully, your furnace is a direct vent so combustion air is drawn from outside. NEVER run the range top or oven unit for extra heat.

Perhaps a heat resistant hood to deflect the heated air flow down and prevent that stagnant air on the floor?

Make sure your hatch over the power cord is closed. Air leaks are really noticed in the slide ins. I have a screen under my waste water drain and that leaks a lot of cold air. Avoid opening the main door.Once your fire the heater stay put either in the shelter or the camper.

I noticed the roof hatches are much colder than the side windows. If I did a lot of cold weather camping that would be my first place to start an insulation project.

I also open all the compartment doors to help warm the whole shell. My heater runs steady for the first hour to get the chill out and then cycles.

 

I agree that you should insulate the floor with hard foam insulation, as well as the areas around the wheel wells. Since that is often storage with an access door, you have a bit of a trade off, but you can work with it.
I also agree about the small 12 volt fan. Put it near the top, pointed down, out of the way, and run it a few minutes before you get up. That will stir the air.
Avoid a cat-heater since you need adequate ventilation, and that just defeats the purpose, plus creates a respiratory risk. Same-same the stove: don't use the stove to heat all night, since you will NOT wake up in the morning. Of course you can use the stove to cook, but people are up and stirring, and the door is opening and closing, so there is plenty of ventilation.
Remember that the rig is sitting up in the air, the breeze can blow under the truck all night, and it can really get cold under there, so you won't have the fully warmed room like you do at home.
One thing I do is place the ice chests outside along side the trailer (works the same for the truck), park next to a bunch of bushes, Turn the outside table on it's side next to the rig, park the quad next to the rig, cover the wheels with those covers, anything to stop or partially block the wind from passing under the rig. Air movement through or under the rig will drop your temp, and make it hard to either raise the temp or maintain it.
I also tape shut any small doors that I won't be using (from the inside) and fill empty bins with foam. I use the trailer a lot, so there are very few epty bins

I recently replaced an archery target, and disassembled the old one. There was a lot of closed cell foam sheets in it, of various thicknesses. Since I was having a problem with draft along the wall side of the bed, I propped these squares against the wall and duct-taped them, including covering the access door. No breeze!

 

I found an insulated duraboard at Lowes i think i may try.
It is an ABS textured vinyl sheeting with a 1/2" foam insulation sandwitched between two sheets of the vinyl
I may cover the entire inside walls with this material. It is paintable and think it would really add to the heating solution. It is quite lightweight and is at 30.00 for a 8.4 sheet so not much cost involved.
Have a 3M spray contact cement they tell me will hold it to the existing "clean" walls.