Thru Hull Sizing and Sharing

I am building a 56 foot ketch and am looking for sizing information for thru hulls. With inflow and discharge for M135 main engine, 7.5 KW generator, two heads, three sinks, three AC's, refrigeration, and a water maker---- I need to use some manifolds to share thru hulls for inflow and possibly discharge.

Have some flow rate data and understand that some devices require scoops. Seems as though all manufacturers want a dedicated set of thru hulls for their particular product. That would leave me with a hole drilling project for 20 or so thru hulls- not a good prospect for all of the usual reasons. Short version is that so far it seems to be that intake can be shared more easily than discharge. The water closet idea.

The engine is a M135 Perkins- at 17 gpm. I am considering adding a manifold for the generator, aft electric head and aft 10k AC to the engine 1 1/2 inch thru hull. Forward would be a second 1 1/2 inch thru hull with a manifold for 6K AC, 14K AC, galley sink pump, refrigeration cooling, electric head and a water maker.

Discharges would be 1 1/2 inch dedicated thru hulls for each head and the galley sink, 1 inch for each of the head sinks. On the boot stripe are a 3 1/2 inch main engine exhaust, 2 inch generator exhaust, three AC discharges and a refrigeration discharge.

--Anybody out there have design experience and data on a clean sheet boat or ideas from production boats?

--Any design data on sizing/sharing of thru hulls or articles would be helpful as well. My searches have not been very helpful.