I use the upper U bolts for a diffuser plate. Do not monkey around with the lower U bolts. The guys who designed the BPS have them there for a reason. It creates the correct amount of draft to keep the fire going. Be sure the sides of the pizza pan do not interfere with the vent holes. You can most likely get away with only 3 vent holes on each side on the bottom. I would not do less than that to be honest.
The stepped drill bit that comes with the kit is not the best thing in the world. It will be a major buzzkill if you are using it with a battery powered drill. A lesser buzzkill if you use it with a power drill. I bought a better version of it at Home Depot for around $40 and was very glad I did.
Overall, I am very happy with the BPS.
Primo Oval XL, BPS drum, Weber gasser