Trimmed the excess flange off of the seat belt brackets, being sure to maintain 2d edge distance from the mounting hole. Filed the raw edges smooth and finished with sandpaper.

Primed the F-705A, and the bar stock that makes up the aft spar & doublers with Tempo Zinc Phosphate.

Also primed the raw edges and holes in the seat belt mounts.

Primed everything outside and then just carried the whole rack into the garage to cure for a day or two.

EDIT 8-26-2020

The instructions say trim seat belt anchors as needed to clear ribs etc as long as you maintain 2 ED from the mounting hole. The print backs this up with a detail view showing the max area to be trimmed. Industry standard is 2 ED from the hole center in a ton of applications, so It seemed to make sense to just trim all of them to a little over 2 ED and call it good.

BUT, I started thinking a little more about this yesterday. The print also shows that there is only interference on one anchor per pair, and the two inbd sets need much less trimming than the outbd. It also shows that on the outbd ones, you countersink a rivet so that the flange of the untrimmed one can lay flush without being trimmed.

I don't see why 2 ED on all of them would be a problem, but maybe they depend on the bigger footprint of the untrimmed one for lateral rigidity once the set are bolted together?

Anyway, I ended up calling Vans and this is the reply I got back from Builder Support.

"This is a grey area, we have only tested the parts as the plans show. I expect since you have acceptable ED this would be fine but cannot give you a 100% guarantee on these. You will have to decide for yourself if you want to replace them or move forward with what you have.

Sterling"

I don't do grey areas, so I ordered new flanges and will replace the ones that don't get trimmed.