What would Mike Holmes do?
This is meant as a tangent. Do it right.
Wouldn't it be great if somebody built a trailer with the intent of keeping it at 68F while the outside was -10F? AND if would have to do this for five days with the onboard fuel.
Use preformed 7'x8' sectional panels with all ducting and conduit installed. Trailer lengths would be in 8' lenghts depending on number of sleds to hauled.
Rolll up insulated door to isolate 1/2 of the trailer if desired.
Option the repair/occupied half and partitioned half with radiant heating for use when shore power is available.
It should be a gooseneck to provide easy hook up and best towing profile . Then finish it with axles-less independent suspension like the GMC motorhomes used to keep it low.
Sounds like a unit The Foose, Mike Holmes, and Airstream should build.
What else?