Hydraulic drive

[homebuilt]

Hi, I am planning on building a wooden pontoon boat 8`wide x 16` long.
We have a place on a beautiful small river with sand bottom. Just want it to cruise about 7-10 Km/hr 2 people. So structural requirements are not as important as a live aboard vessel. I would really like to drive it with a paddlewheel. I was considering a 10hp diesel engine(economical price from supplier)
Wheel would be approx. 4` wide by 5` diameter.
Maybe electric thruster on front for steering (solar panel)
Would need a low speed high torque motor .
Just not sure about hp requirements,pump etc. Any suggestions would be greatly appreciated.