Here ya go Greg.
30 Gallon blue barrel from
http://www.bayteccontainers.com/
Input plumbed via a quick disconnect to a Y-valve off the washdown pump. Overflow goes over the side via a larger hose plumbed near the top of the tank.
All the fittings and hoses came from West Marine.
Tank sits on a cooler mat from Melton Tackle and a ratchet strap goes around the tank and roof support to hold it in place.
You can still open the drawers on the dinette and the tank isn't in the way at all.
Last week while Hook & Lining I had over 300 spot in there for over 6 hours without an issue.
I cannot possibly imagine a better set up on a 27 Judge.