pontoon / cat style air prop boat.

In the world of single place Ultra light PPG,s and Delta trikes that are FAR 103 legal with a max weigh at 245 pounds., whats your take on using the chassis and motor pod suspended between pontoons or even a tunnel hull. There are a few floats out there for water take offs , But what about a purpose built hull to place the aircraft frame more in , that on for a low CG . No wing , Just single place air boat > A prop swap may be in order for best thrust over a air prop.
I am looking to extend the function of a PPG trike .
http://www.trikebuggy.com/blackhawk/bigpics.htm