A camper or boat trailer large enough to need a big truck to pull it will already have is own brakes.

The biggest reason for a heavy vehicle aside from the pulling ability is that the trailer can overpower the main vehicle when quickly changing lanes due to the whiplash caused by the sometimes 20+ ft distance between the front (steering) wheels of the truck and the hitch. It's actually why there have been a few experiments with 4-wheel steering for trucks over the years.

A remote towing vehicle would be able to significantly reduce the distance between the steering and the hitch.