Towing 4 down v/s Dolly.
Well both have their advantages
Dolly towing you need not modify the towed car in most cases.. And it is very easy to change toweds. HOWEVER.. there are some downsides too.
First and foermost is "What do I do with the dolly when parked" Depending on your motor home and the RV park this can be an issue.. Where I'm at now. not so much but in some cases it's major.
Second... Hookup is a lot "Trickier" and more work, You have to drive on square, and strap it down,, Then you have to drive a bit and re-check the straps.
Finally stopping... You have brakes on the motor home, and on the dolly, but NOT on the other two wheels on the car, so this increases your "Skid distance" should you panic stop.
Towing 4 down.. You do have to modify the towed (Add brakes, base plate and some kind of tow-light or diode system) thus makes it more expensive to change towed.
Plus you may need to make "other" modifications (Lube pump, Axle lock or drive shaft disconnect)
But hook up is fast and easy You need not be "Square" at hook up and ALL wheels brake when you stand on them.
Given a choice.. i'd 4-down.
Home is where I park it!