tow dolly vs. Tow bar

Not sure about the "only way to go" as lots of people use dollies without issue. Yes 4 down is a little more convenient but also more expensive to set up. Dolly towing opens up a lot more possibilities for tow vehicles as basically any front wheel drive vehicle can be dolly towed. Once you have a 4 down towed, it is a pain to switch vehicles unless you buy the baseplate and lighting for the new vehicle. (Cha-ching!)

For the record, we have done it both ways and are currently using a dolly because of the vehicle we are towing.