I would just use the thru hull pickups for the engines and then use the water that flows thru the drive to feed drive showers and/or just dump it back on top of the drives.
I had this set up on Pantera and it worked great. If I didn't already have Simreks, this is how I'd do it. It also had separate dump on the side of the boat for excess water going thru the drive to dump out. That dump was already there before I did the shower or I would have dumped that water down onto the drive as well.