so, the problem is never the "pulling", a Yaris can get a mid-size camper up to highway speeds no problem. The problem is controlling and stopping, and that's where the length and mass of the towing vehicle comes into play. A longer and heavier tow vehicle is more stable, and a vehicle designed for towing will have bigger brakes to handle the increased stopping load.
Which, of course, also means that little tow robot will be even more useless for towing than the car it's following.