Towing with Refrig on gas

Just a question, not that I would do it and this post does not address the legality or safety of such, but just want to know...

If you towed with the refrig running on propane would the heat that is expelled through the outside vents leave marks on the inside of the shells? Has anyone one had experience towing while running the refrig on propane while towing and what were the results good or bad.