We towed a Kia minivan on a tow dolly for a while.
One of the big problems you have with towing a minivan on a dolly, has to do with weight limitations. Minivans are heavy, many weigh well over 4,000 lbs, some close to 5,000. There's only a handful of tow dollies made that are rated to handle that much weight.
Also, many Motorhomes, the weight limit on the hitch receiver is 5,000 lbs. Add the weight of a tow dolly to a minivan that in some cases is getting close to 5,000 lbs by itself, and you frequently will find yourself over that 5,000 lb limitation of the MH's hitch receiver.
Also, as already noted, width and fender clearance can be an issue.
I agree with a previous post - The Acme EZE tow dolly is probably one of the best choices if you are going to tow a minivan on a dolly. Thats what we used, and it worked great. It is one of the few dollies out there that is rated to handle 5,000 lbs, yet only weighs about 400 lbs. That, and the way its designed, pretty well eliminates issues with fender clearance, taking sharp turns, etc.
Will and Cheryl
2021 Newmar Baystar 3014 on F53 (7.3 V8) Chassis ("Brook")
2018 Jeep Wrangler JK ("Wilbur")