I came across several shots of the 'Canoe Bike' which seems to be a custom build by Jay Broemmel. There are several action shots of this vehicle on the internet. There are a couple of similar ones also, but this one looks like it might be functional.
There are even images of it in the water.
It seems to be based on the commercially available Autocanoe design.
Jay's version seems to be bike additions to a used aluminum canoe, while the Autocanoe appears (from the video) to be a bike with a flat bottom boat built around it.
For my planned trip from Pittsburgh to the Gulf of Mexico, would a design along these lines be viable? My trip is planned as a pleasure trip going down stream, with short land trips. I am not overly worried about efficiency, but it needs to be able to pedal up some hills (slow is ok), be able to brake going down, and have enough energy in the water to stay/get out of danger on major waterways.
The primary concerns are longevity and safety. Can one of these survive a 3300 mile water/land trip? Will it leak un-manageably or in some other way be unsafe?