I have a F-350 long bed CC and have towed both a 34' and currently a 40' 5er. There is some very good advise above. Personally, I go a little slower than the speed limit and travel in the right lane when safe to do so. By traveling in the right lane you not only let everyone pass you, but you are allowing a safetly margin should you have a tire failure.
Should you have to pass someone, never take the other driver for granted that they will let you in. Many persons will speed up as soon as you put your directional on. Give yourself plenty or room, be sure your mirrors are set right, and know your rv and truck habits when passing. Even though you can not see the end of the RV you should know when you are passed the other vehicle.
Keep your cool an drive with 100% concentration on the road, the conditions, traffic pattern and defensively.