Tow trailers- For all-wheel as well as 4-wheel both open and enclosed towing trailer are good option. There can be the risk of transmission damage as all wheels will be off the ground. But in case of enclosed trailer, there will be increased security as well as added protection from elements. Make sure that you really need these features or not as renting a trailer can be more expensive than a dolly.
Tow bars- To connect the towing vehicle with the towed vehicle we use this system design which is also known as coach. But don't confuse this with tow hitches. The tow bar is attached to both the vehicle in such a way that it can move freely on the road. Connections by chains are also needed in order to be safe. The tow bars are not much strong and secure option and that's why they are less expensive. It is advisable to go with the previous option if you are travelling long distance at high speed with bumpy roads.