Hi Don,
The hitch head, shank, and WD bars are a part of the load carried by the truck and should be counted against the GVWR of the truck.
When you weigh the truck, because of the above, leave the whole hitch in the trucks receiver, WD bars and all. You can take the WD bars out of the hitch head and put them in the back of the truck if you wish but they should be weighed along with the truck and not the trailer.
Barney
2004 Sunnybrook Titan 30FKS TT
Hensley "Arrow" 1400# hitch (Sold)
Not towing now.
Former tow vehicles were 2016 Ram 2500 CTD, 2002 Ford F250, 7.3 PSD, 1997 Ram 2500 5.9 gas engine