2wd or 4wd? 2wd generally sit lower. If you're already low on the rear then dropping 2" more would certainly drop the landing gear more. Did Keystone messed up and install the landing gear installed too low?
OP, is the 5er sitting level thru all this? If the 5er is level and the landing gear are too low then it could be a mess up on Keystones part. Your truck being an 01 is 14 years old. How worn are the rear springs? Have you done any upgrades to the truck?
Question is if the 5er is level when hitched and the rear of the truck is not below the front then it seems that the landing gear is wrong. I just don't see how the landing gear could hang down too far if the 5er is sitting level when hitched unless it was installed wrong.
I would start looking at the 5er and then re-access your truck.