If you can look after its requirements electric is a fine idea.

Situated on the rudders is possible, but it would be limited to the rudders angle limits, might want to beef up those rudders and mounts too.This form of drive is such that it can be controlled in thrust direction independent of rudders quite easily as there are no fluid lines to worry about.

Commercial units are a lot easier to haul in and out of the water completely, and their compactness enables stowage in tighter spaces. Alternately you could play with fitting a motor on to an old outboard leg. Lots of possibilities