The factory yellow boards came with the distribution rings, like the red, so if you paint your own you will need one set of your white boards. I think you'll find everything will flow better the way your going to do it. The only thing I'd add is if putting the KSU above makes your blue board too low than just put it to the left of the red and dress your cables in. You don't want to be on your knees working on stuff.
Edit: To correct side of red backboard to place KSU
