http://i293.photobucket.com/albums/m...psqafzou9q.jpg
Here is a 30 gallon stuffed under my console. Its not as big as you think. This tank originally came on a carolina skiff. This one I belive can be used above or below deck.

What's holding that tank down? Looks like it'd go flying in heavy weather.

When I bought my 1975 V20 it had only saddle tanks (40 gallons total). I wanted additional range for offshore fishing runs, so I added an 18 gallon Tempo Model TP18SC under the bench seat that I added in the rear. I routed each of the tanks into a three-way manual switch that I mounted on the starboard side of the seat. That setup has always worked great for me.

Here's a photo of the seat: http://www.wellcraftv20.com/gallery/album06/H. It opens from back to front to give access to the tank, which occupies about 90% of the underseat area. Unfortunately I don't have a shot showing the seat open.

Hey there fitz, glad to see a old timer still checking in!!!