A motorhome towing a pickup with a boat behind the pickup? Overlength will be only one of your problems. That's an illegal combination in most if not all states.
As far as state police/highway patrol bothering you? Just because one guy does it and doesn't get stopped is absolutely no indication that you will. It's not a game of percentages nor is it a defense that 'the other guy did it and didn't get stopped." Your problems if stopped will be a whole lot more than just paying a ticket. It's going to make for a very long day and very expensive. People just don't have a concept of reality when it comes to getting stopped.
The strangest combination I ever stopped was a motor home pulling a box trailer that was pulling a Dodge Durango with a boat attached. 4 vehicles in combination. He had started out in Missouri and I got him stopped almost 100 miles into Illinois. His complaint was he had driven all that distance and no one had stopped him. Whine and moan. Well, his tough luck. Just because he managed to slide for 100 miles he was stopped then. His pickup and boat was towed to a lot since he didn't have another driver for them. He pays the tow bill and the storage bill. I nearly got writer's cramp writing tickets. And 2 or more tickets is a mandatory court appearance. That's a state supreme court rule. And court is not right then either. 30-45 days later. So another trip back over 100 miles to court.