I hope your doctor cleaned you up as well as my wiring!Your wiring reminds me of my angiogram.
Separate thrus and seacocks are preferable but if the boat doesn't have a raw water system and therefore no thru hull, it is easier to use one of the existing pickups like the livewell for the source of sea waterMy 2003 228 has two thru hulls and the live well is on one and the raw water wash down is on the other.
Hookup, am i seeing this correct? You have a livewell pump which discharges into the intake of your washdown system? That seems genious. More pressure in should make the pump run great? Is that the case?I have two Rule baitwell pumps that screw into the thru hull shutoff valves. Both have dual ports. The pump circled in lower right corner you can see the short hose coming out and connecting to the Shurflow washdown pump. The Rule baitwell pump goes to a external baitwell on deck and the Shurflow washdown pump goes to a bulkhead mounted hose connection.
Originally the washdown was connected to this thru hull. I added the dual port baitwell inline. Power for the baitwell pump was added. You can see switch next to last battery switch (bottom).