Dave,
Here are some pictures. The first looks down from the top, starboard left, the tiller in the foreground. I carry one 20 pound tank port, one starboard. In the picture I have the port tank removed for refill, so you can see only the starboard tank (white) in place.
Below, is a view seen from the starboard side. From bottom right to top, see the starboard tank (white), a 2.5 gallon lamp oil tank (green) and the wooden platform for the port side propane tank. The platform (plus a strap), holds the tanks securely, and it raises the tank an inch or more off the floor. That keeps the tank out of seawater most of the time. The drain in this compartment is frequently under water, thus washing the floor with seawater.
The propane hose fitting (lower right) has enough slack that I can simply turn it port or starboard to connect to either tank. When one tank runs dry it only takes a minute or two to switch.
I have a few more pictures
here.