It's just plain being smarter to drive at 65 or under. I doubt that you will find semi trucks driving at 80+ mph. Driving faster than 65 is more dangerous and is harder on your TV and trailer. If you ever have to make an evasive maneuver at 80+ mph, you may never live to tell the story about it. Wind resistance goes up as the square of the speed, so at 85 versus 65, the wind resistance is 1.7 times more. You better own an oil field!
If you think you can drive at 85 with a trailer behind you, good luck. If you pass me, I will slow down in case you end up in an accident that might involve us.
I used to hate being stuck behind an RV when I was younger. With a passion along with appropriate cuss words of course. Now that I own one, in a weird sort of way, I enjoy seeing the cars lining up behind me as I cruise along at 60 mph, hehehe! It's almost become a new hobby.... I think of it as slowing people down to a safe speed to help save lives! :D