There is more and more vertical movement at the back of the 5'er as it's length increases. I'm sure those of us with long 5'ers have experienced movement to varying degrees with "stuff" stored in the very back while traveling. I have a rear mounted TV that is on an electric lift that always travels in the down position so no problem there since it is bolted down. The rest of this rear area has an electric fireplace with storage shelves on either side. I used to travel with a PlayStation 3 on one of the top shelves with the door to the shelf closed. Again, this shelf is on the back wall of my 5'er. After a few hundred miles the PS3 had obviously moved up and down while traveling enough to actually break through the shelf floor and ended up, shelf floor and all, sitting on the stuff in the lower storage area which is right on the floor/carpet. I replaced this piece of shelf with 1/4" plywood using the old broken piece as a template and also moved the PS3 to the bottom floor position. With this experience with the PS3 I can not even imagine having a rear kitchen in a long RV with shelves full of dishes/glasses, etc. I am a very non-aggressive driver so my driving style wasn't the problem.
Now back to towing behind the 5'er. With this much vertical movement that is obviously there, what impact will this have to a trailer being towed? I have seen this configuration on the road and the movement is very obvious as I am being passed and watching stuff on the trailer bouncing up and down.
The bottom line for me is No Way, No How, Never! It just isn't worth the risk to me not to mention the states where it isn't legal including the state I live in and usually travel to or through.
2006 GMC 2500HD CCSB 4x4 Duramax/Allison, Titan 52 gallon fuel tank, Prodigy Controller, B&W Companion Hitch
2010 Jayco Designer 35RLTS, Cummins/Onan RV QG 5500 EVAP, Progressive Industries EMS-PT50C, TST Systems 507 TPMS, RV Flex Armor Roof