Yep, that sucks, we always drive a second vehicle as first of all, we don't like to drive the truck to sightsee, second of all we like to have our Jeep to go offroad so we both drive. It really sucks to have to pay for another vehicle but if that is what you want to do, expect it and if you don't have to pay that is a plus.
If you tow behind a MH you generally don't have that problem, just us 5th wheel folks have to pay. Therefore my comment about it sucks!
I have to comment on the 3rd vehicle part, first of all my camping unit does not have the ability to move on its own so to my way of thinking it and the truck is one unit, the second vehicle is like a toad. I ran into this with the BLM folks, they tried to claim the truck and trailer was two separate vehicles, I told him explain to me how that trailer was going to move on its own. LOL!