Agreed that it compresses, but at rest my bottom plate is basically level...
I think I know why - the mounting holes on the 5er may be different than yours...
my 5er 'receiver' has say 5 holes running vertical in the front and 5 more toward the back...
my trailar is not in the same 'height' holes - the front is in hole 3 from the bottom and the rear is in hole 2, thus pointing my hitch upwards so the bottom plate is level and easier to hitch...
Ah - also noticed the OP has a 21,000 lb trailair! mine's 'only' 18k :)
heavy boy you are towing there !!!
I'm trying to plan a summer trip to cooler climes than north Texas, maybe I can use the hitch as my excuse to run to Colorado :) :) :)