After reading the "Sticky" thread in the "Towing" forum on the Open Road Forums and some communications with Ron Gratz, I worked up a spreadsheet using "LibreOffice Calc" in the free Libreoffice Suite that I used to approximate what size weight distribution (WD) hitch I needed. I had Libreoffice save it as a MS xls spreadsheet file. The link to the spreadsheet is at the end of this post.
My spreadsheet is an obvious overkill, because most manufactures of WD hitches only use the travel trailer (TT) tongue weight, the hitch weight, the load weight behind the rear axle of the towing vehicle (TV) and the total loaded weight of the trailer to determine the size of WD for their customers.
I had fun putting the spreadsheet together, but I need some more eyes and brains to critique the spreadsheet so I can make improvements and find errors I made so I can correct them.