Go to...
"Boat Info" tab in the middle of the HOW main page, click on "Model Info" and use the drop down on far left margin to select "35.5", then drop down to "Improvements". Look for the photo posting of a project by Jim Rushing. Thats a start. As I recall, his was custom configured to fit under setee(sp) in salon, but newer models my be out now that will fit the 35.5. Issues are: where to install raw water intake, where to install main unit, and running ductwork through shower/head area to aft cabin. All these things can be done if you keep everything on starboard side. Since you are on a lake, you could probably pull water off your head discharge thru-hull, although that is a long run. Read Jim's article.