Since both the jeep and trailer are narrower and shorter than the RV, you probably don't get much extra drag. What kind of mileage do you usually get in that rig?
I don't have 100% accurate numbers at the moment, I only just bought a heavy truck Scangauge on this trip. The previous owner said he got around 11mpg, but that could be at 55mph / not towing / not much in the water tanks / and no generator while driving. I was doing 65, I have slightly smaller tires on it right now (new for this trip) and towing with the generator on and full water tank. On the previous tires which were taller, I *think* I was getting around 9mpg with the generator running, but I was also running faster then too. Once I have a chance to put some miles on at the same speed but not towing, I can get a more accurate image - I'm not impressed with these tires though, they will be getting swapped out again when I have the chance. I'm going to try and sell the old ones first, then I'll pick up another set of used truck shoes, swap them, and sell these shorter ones. Buying used for $75 each is WAY better than new for $500 each!
How'd you get away with that? It is illegal in Alabama, Florida, Georgia, North & South Carolina.
Officially, tandem towing is allowed only with a CDL, yet I have seen more and more 5th wheel RVs towing tandem. Nobody seems to care about them. I've also seen a couple HUGE motorhomes (one that has been on TV a few times) with bumper pull cargo trailers behind, and a bumper pull BOAT behind that. Way longer than my setup.
"escaping from Irma"
I'm guessing the "powers that be" turned a blind eye in view of the circumstances.
I agree with this as well. I fully expected to be pulled over at least once and hassled with, but after driving past no less than 50 troopers in 3 states while going in both directions (these guys were EVERYWHERE) and they were definitely running enforcement on the way back... Nobody even blinked at us. Fate protects fools, little children, and ships named Enterprise.