Trailer Life Article about GCWR...etc.

Again, no matter what you do, YOU cannot change the manufacturer's rating for your vehicle. The manufacturer knows what gear was in your vehicle when it left the assembly line.

Also again, manufacturer's ratings are not enforced except in regard to warranty claims, so what difference does it make? Unless you go into the service bay towing a trailer, the manufacturer doesn't have any idea if you have ever exceeded the rating.