I would not go the electric trolling motor and battery route Ed. I used this set up before I built my first mini mud motor. For my use, there way too many drawbacks.
1. The weight of the battery.
2. The life of the battery in cold weather hunting.
3. The depth of water the trolling motor required to be useful. I believe it was close to 1.5 feet to run well.
4. When the water got shallow, I had to turn the motor off and somehow raise it, get out of the boat, drag the boat upstream, put the motor back down and start up again. Going up shallow streams, and having to do this many times, it plain and simply sucked.
5. Plastic prop (although you can replace with a Young's prop as you know).
6. Speed. The 55 lb electric I used could not get the boat going very fast. Made for long rides in the morning.
I still can't believe that someone other than Rickshaw hasn't come up with a lightweight small mud motor. Maybe a 2-3 hp unit that weighs in around 30 pounds or so. I've got to believe it possible. Mine weighs in under 15 lbs and the rickshaw around 20lbs isn't it?
Can always go with these guys.
http://www.longtailboatsps.com/
He posted quite a bit on the Boat Design Forum page about the mini longtail. His kit was quite interesting and dirt cheap. He used quality parts. Only downfall was shipping from Thailand. I don't think he put much effort into determining shipping rates as I ship stuff over there all the time for 1/20 what he was quoting.
Mark W