I seriously looked at electric propulsion for my boat, singe engine. A close friend is a retired BC Ferries captain and I discussed electric, gas, and propane propulsion. The conclusion we came to was that although electric and propane would be suitable for dinghy use alone with my desire to use the motor as an emergency back up in case my main engine pooped out I would be better off with gas. Range would be a problem with electric when pushing my sedan cruiser along, propane would be an issue if my main source of propane had been used for other tasks. And in light of my dinghy motor being a back up motor, we both came to the conclusion that the highest horsepower the dinghy could legally handle would be the way to go. So in the end I got a 9.9 short shaft gas engine.
Epropulsion has a good reputation and the MinnKota trolling motor will get the job done if you aren't planning on traveling over any distances such as longer dinghy exploratory trips.