While what the local state representative told you may be correct, I have never seen a privately owned pickup truck with a weight class sticker higher than the one for the truck itself. However, I have seen pickups with Lower weight class stickers. For example, my F250 (8,800 lbs) is a weight class 3 (7,001-9,000 lbs), although I have seen the same truck licensed as a weight class 2 (5,001-7,000 lbs). This is perfectly legal, though, as long as the truck's weight doesn't exceed 7,000 lbs.
By what the local state representative says, I should paying $355.00 instead of the $153.00 (that I just paid two days ago) to have my truck licensed as a weight class 7 (17,001-21,000 lbs) instead of a weight class 3. I arrived at this weight class being that my truck can tow a maximum of 10,000 lbs plus the gross weight of the truck (10,000 + 8,800 = 18,800 lbs). I don't know what the actual weight of my combination is but it must be under 15,000 lbs because when I travel the PA Turnpike, my toll always charged as a class 2. However, I could save myself $67.00 and legally license the truck as a weight class 6 (14,001-17,000 lbs) for a mere $288.00 (aren't numbers fun, folks?).
I find it very interesting, though, that you can license a motohome as a class 3 (11,001 lbs or more) for only $81.00.
IMHO, If your truck was towing a trailer for commercial purposes, then you should be paying by the combined weight since commercial vehicles are subject to weigh stations and other spot checks. However, I think they "look the other way" when the trailer is an RV.
When was the last time you (or anyone else for that matter) were stopped and weighed while towing an RV to ensure their TV is licensed in the correct weight class? I've been pulling (RV) trailers for over 20 years and have never been stopped yet. Unless "Fast Eddie" (what we call our state governor for the readers of this post who are not PA residents) decides that here's a new way to make a fast buck, I seriously doubt there will be any changes to enforce this on RVers.
2009 GMC Sierra 2500HD | Crew Cab | Standard Box | 4WD | Duramax/Allison
2000 Jayco Eagle 266 | FBS | TT
1986 Coleman Laramie pop-up -- Still in the family!!!