I love driving an RV. In almost all cases, I'm bigger and that counts.
First rule;
Throw away all your rear view mirrors.
Second rule;
Don't use side windows.
Third rule;
Get the loudest horn you can, or several horns if you want plenty louder.
Fourth rule;
Get driving lights and mount them to shine in the guy's mirror in front of you.
Now, when changing lanes, turn on your flasher, count to 3 and turn. You'll hear horn honks. That's a good thing. Tells you the other driver is paying attention. If anyone cuts in front of you. Lay on that horn and see if how close you can get to them. If it's dark out, turn on those flame throwers and blind the bastard!
Carry a squeeze bottle, like what catsup comes in, filled with the last drain from your black water tank. When someone wants you to roll down the window to discuss your driving, squirt a little his way.
Oh, and laugh. I once laughed my head off as a guy was cussing me out. He asked me why I was laughing. I said this wasn't MY RV. He finally realized that meant I didn't give a **** if it got a bump or two. Of course, he did care about his car.