That is a pretty long receiver adapter. I bet your tongue weight will be pretty darn low. I think I'd flat tow the toad, that won't put any weight on your long receiver adapter and you can add remote brakes to your toad as well. Motorhomers (new word) do it all the time. However, if you flat tow it has to be a car capable of flat towing.
I'd say the alternative is a tow dolly (minimal weight on the long receiver adapter again.
I'd say a trailer is the last resort because of your tongue weight.
I would, with that receiver extension, add weld on eyes near the end on each side and lengths of chain with turnbuckles attached to the truck's bumper at the ends. That will remove any slop in the extension (which could be quite a bit at that distance and make for a better towing experience.
Jut my opinion, not that it means a whole lot....