I think a proper tow dolly setup is safer than a vehicle towing more than it can handle.
But that's really the point isn't it.
With a proper trailer you have tongue weight and trailer brakes. If the load is placed correctly on the trailer and does not overload either the hitch (tongue weight) or trailer brakes, a trailer is going to be pretty safe.
With a tow dolly you don't have brakes and your tongue weight almost certainly went up.
If 40% of the weight of the towing vehicle is the limit for the dolly and load before brakes are required on the towed load (as they are by law in the state where I live), your towing vehicle needs to weight about 10,000 pounds to tow a 1/2-ton truck with a dolly.
If you are not setup with an adequate tow rig your dolly setup cannot be labeled adequate. End of story. You may get away with it but don't confuse being lucky with being safe.
With a dolly your margins of safety quickly gets down to zero.
If you are pulling with a 1/2-ton or smaller pickup, or maybe even using a car, and your load is a complete truck there just isn't any way to make it 'proper'.
Too many people here are responding that they got away with it just fine and ignoring that in many states they violated the law their legislature has put in place and that they are playng fast and loose with the laws of physics everywhere.
If I die young I intended it to be cardiac issues or cancer. I'll leave the stupid towing tricks to others.
