Hi 1Step;
First off my boat is a 23 CC with a 32 custom tank I built and moved forward just behind the leaning post. It is mounted under the deck so some of your problems could apply to my set up but I Do Not have any back flow from my overflow hose. I did have a 18’ Hydrasport boat and mounted a live well tank Above the deck. I felt on that boat it would be the best way to go.
FellowShip
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Just for the Grins
Official Antique Classic SeaCraft Owner