Back in the day....our 45' coach with the full-size truck and Rzr in the back was 72' long. Actually longer since the tailgate was down.
Never had a glance by the police in our travels. But I think a trailer would attract more attention since it "looks bigger".
I wouldn't worry about it though.
My current stacker is 35 feet over all tip of tongue to rear door. The box itself is only 28 feet. The new one can be made to whatever length.. I have pulled a stacker from the Florida keys to Las Vegas Utah Arizona. All of the south, up to South Dakota. Indiana Illinois .. Pretty much over half of the US.. I have even been pulled over speeding with it and have never been ticketed or checked for length.. Rule of thumb. If it's plain or the paint matches the coach you probably won't get messed with.. Put logos or racing numbers on it. Probably will.
I have driven over 200,000 miles in the U.S. with our rig, which totals 71' , and have been ticketed 1 time for being over length. Guess where? Ca., of course and that was before the law governing Coach length, in Ca., was changed from 40' max to 45'. When we were ticketed we became very concerned and talked to every authority we could contact to see if we were going to have to change our set up. Talking to different State Police Dept's the bottom line was that they didn't want to pull our rig over to measure because of safety reasons. By the way, we were not really pulled over in Ca. but were leaving a truck stop Ca. , where a DOT officer had a reputation for waiting for big rigs to leave and getting them before they got back on the highway. This officer gave us 3 tickets, one for the total length, a second for over length Coach and, get this, a third for being too wide because of the Awning!! When I questioned him about the width issue, he became a little disturbed and ask me "Just how many f-----g tickets do you want?" I didn't speak again. We obviously had run into a little trap. He made us drop the trailer and hung around to make sure we didn't try to tow it out. We had to find a tow truck to take it to the race track. We never had another issue in all those miles. Almost every racing rig is over length and those guys never get tickets, except for speeding. I think it is a non-issue today. As my wife said when we got those tickets, "think about those tickets as a small fine for all the violations you've committed and gotten away with!" Ah, yes, the wisdom of a woman!