Not sure how far you are with the build so this might not be relevant any more, but have you thought about getting the upper half of the 2 centre posts set at an angle.
The reasoning for this is if you’re going to use your rack for benching, especially for incline or decline work.
I recently got a rack myself and the posts are straight like in your diagram and trying to lift the bar off when doing incline bench presses is a bit of a pain when you don’t have a spotter