I dont think thats true. Nv requires at minimum an endorsement for pulling recreational doubles. If another state is reciprocal on the dl then i would be able to tow in that stae with my Nv with endorsement. Though the other state probably wouldnt know what Nv requires, i bet if you were stopped they would inquire or possibly cite you and let the court decide. I was stopped in Ca years ago pulling doubles and i showed the officer my dl with endorsement and he said he couldnt believe that it was legal even after showing my dl. I now have a CDL with doubles and triples endorsement and dont worry about it no matter where i go as long as i know the state i am traveling in allows doubles.