I pulled my truck on the scales with a full tank of DEF, full tank of fuel, ready to go camping with wife and two dogs. Steer axle was 5280# (Front axle). Drive axle (rear axle) weight was 3860#.
Weighed again with 5er hooked to the truck...at that time the Drive axle (rear axle) weight was 7200#.....Take 7200#, subtract the 3860# and you get the pin weight of the 5er @ 3340#. Pretty simple. The combined weight was 25,240#.
Trailer axle was 12,580, so add the pin weight of 3340 and you get the total weight of the 5er, which was 15,920#, GVW of the 5er is 16,950#. ( so I'm under 5er's GVW by a little over 1,000#.
Just some simple math...weigh the truck, ready to go camping, then weigh it again with 5er hooked to it...subtract the weights as I did above and you'll get your actual pin weight.