Well I crossed the Mighty Mac in MI last week and the MIDOT doesn't agree with that LEO. A two axle MH is charged as a non car for a total of $10.00 while a car is charge $4.00. Any non car is charged $5.00 per axle. My two axle MH towing a car using the tow bar setup shown in this thread was charged - per the electronic display - a "Combo Rate" of $14.00 If the MIDOT believed that my rig was 'one unit' according to the convoluted logic of the OP, that single non car unit with 4 axles would have been charged $20.00. So I guess if I were the OP and got the "it's a single unit" opinion from an LEO, I'd ask for it in writing and would also ask for some documentation that that particular LEO could commit the state's various law enforcement communities to that opinion. Good motto for the OP might be 'if you have to work that hard to determine if what you want to do is legal amongst all the Barney Fife's out there, then maybe it's too much of a stretch". JMO