RV Roof top A/C Units recirculate the inside air. The return air goes thru evap coil then back into RV via ducts/registers.
Evap coil is inside an insulated/seal cover so outside air does NOT get in.
Outside air is used ONLY to cool condenser coil which is under roof shroud and exposed to outside air.
Heat loss is thru roof vents/fans and windows.
The Vent Insulators you are using takes care of the roof vents
Reflectix Insulation material between window shades and windows will help minimize heat loss thru windows (can buy rolls at most hardware stores)
When we FTd we removed the day/night shade on large rear window and replaced it with 4 black out insulated curtain panels.
Pull panels open during day for sunlight and heat then close at night. Made big difference in heat loss.
Also used Reflectix on windows that the shades didn't need to be opened....one by computer desk and 2 in bedroom slideout.
We stayed roasty-toasty in -19*F temps (2 weeks) and in several stints in less drastic temps (20s)
Propane WAS a hot commodity :B
