Here's an idea that's been bouncing around in my head for years. It's an amphibious bus concept using pontoons that stow over the roof of the bus and swing down on a support system for use on the water.
Here's a breakdown of the amphibious parts in mid-transition. The fixed supports tie into the vehicle chassis rails under the bus:
For water propulsion, I'm thinking paddle wheels roughly aligned with the drive wheels and a telescoping set of forks that extend into the spokes of the drive wheels and in turn spin the paddle wheels. The vehicle's engine could then provide both road and water drive without the need for a complicated water propeller hanging under the belly. The paddle wheels could be installed with a partial channel hull in each pontoon that allows for clean water into and out of the paddles.
For steering, maybe some kind of fold-up front-steer rudder that is controlled by the front wheel. Probably wouldn't need one on each side.
Obviously, a lot of thought would need to be invested in figuring out the total displacement of the vehicle to engineer adequate floatation, and I doubt the pontoons would float the vehicle high enough to just drive in or out of the water without scraping the floats on the ramp, so maybe some kind of telescoping supports for the outriggers that allow driving into the water in a high position, then lowering the floats for better efficiency on the water.
Can you imagine living full-time in a bus that also
can cross lakes and slow-moving rivers? Each pontoon has over 100 square feet of deck space! Add a low-profile roof deck and you'd triple your floor space while on the water. And you could travel the length of the Mississippi from north to south on just a few gallons of fuel.