On my '05 star, I don't use the rear hard tanks at all, waste of time filling IMHO and they don't help much with the wake size because they are too far forward.
My new setup will be (2) 720# X-star sacs from wakemakers in rear lockers
Fill the KGB and add a 750# sac to the walkway
(you could use (2) sacs under the front seats instead of the 750 in the walkway)
This shouldn't take too long to fill while your warming up your engine, getting ready to ride, etc. I would stay away from 2 pumps personally. Make sure you have 1" hoses.
I was njskier on here.