I hear all kinds of crazy stuff about dot and pulling trailers.
I spent some time at the dot office a few months back and talked two officers about all this.
1. If you have sponsors that pay you to advertise for them you are "For Hire" That means you are "For Hire" and all commercial laws including dot #'s and a cdl would apply to you. You would also have to claim taxes for this. If you advertise you personal business or the tow vehicle is registered to your business it is "For Hire".
2. If you race for money you are " For Hire". That means .....
Now they both told me that lettering on a trailer is putting a bullseye on yourself and asking for attention from them.
Above info is what the law is or could be used to give you a fine, but
they were not being butt heads just explaining to me what it was.
Now here is where they were really nice and helpful to tell me how avoid any issues.
1st Simply don't put decals on your truck or trailer to bring attention to myself.
2nd IF A VEHICLE IS USED FOR PERSONAL USE TO HAUL PERSONAL PROPERTY you do not have to have a cdl or dot #'s or any of the other bs you hear about all that. You can tow more than 26,001lbs combined with a truck and trailer combined and not have to have a cdl.
3 You do have to have the proper tag to tow the weight you are towing. Tag office will help you on that.
The officers told me if I was pulled over to never tell an officer on the side of the road that I won any $. The officer has no way to prove you did or did not.
4 A vehicle can not tow more than it's tow capacity no matter if it's private or commercial.
This is probably what the guys in the RV are having problems with.
Different state have different requirements for driving RV's. You would need to find out what your state laws are.
The best thing for you to do is go into a scale house on the interstate and talk to the guys in there. They have no problems talking to you and will HELP you with any questions you have. They are actually there to help you, but once they have you pulled over on the side of the highway most are not going to give you any slack.
I have a friend that got stopped in NC last year with a dullay pulling a 40' enclosed trailer with 2 trucks in it. He was over weight on front axle of trailer and rear axle of his truck. He tried to explain to the officer that he was not for hire and the girls at the tag office told him to put that on his trailer and he did. (I've laughed at him for years and told him this ticket was coming) Officer told him exact same thing I did, it doesn't matter if you are commercial or not you can NOT be overweight combined or per axle. His ticket was $840.
He went to court and again just like I told him it was going to be $840 after he pleaded to the judge.