Bowti, Yes it does make a difference, more pin less chucking, the weight of items in the bed don't help the balance of the 5er. What are you loading into the bed of the truck. We carry all our supplies in the 5er, and they stay there between trips, the basement and front compartment are close to full. I have a 11,000# and try to keep the pin at just over 2,000#.
I do carry the pin tripod and the roll up fence in the tool box in the bed, but that is about it.
The dry pin is about 19.6%, you should try to fill the basement to increase the pin percentage. Does the 5er have shocks, installing them on my 5er helped a lot.