Just wanted to help out anyone who has this question.
Using a 20’ u-haul, I was easily able to load 11 pins and 4 vids. This took up 90% of the floor space.
You should be able to put another 3 pins in there.
Generally, assuming vids and pins have similar moving dimensions, you should be able to fit 18 pins in a 20’ U-Haul’s available floor space.
... Altan