Actually, there are quite a few electric boats out there happily cruising both inland, coastal and beyond. Check out the various companies that offer systems. There are the more "do it yourself" systems if you are handy and really want to be adventurous, or the "drop in type" systems that can still be installed by you to save a bit on costs, but have already been setup for you so you don't have to re-invent the wheel. Mark mentioned several companies (ASMO Marine does have a U.S. distributor in Annapolis). MasterVolt also has systems.
The Elco system at 1000 lbs seems quite heavy - unless they are suggesting a dual battery bank. A 48volt system with 4, 210ah thin plate AGM's should weight pretty close to the weight of your motor, plus the transmission and full fuel tank.
If you want to read about someone who switched 4 years ago and is more than thrilled with his electric propulsion, check out Capt. Mike's blog:
THE BIANKA LOG BLOG: Going electric: Part 1: The why and how
Electric propulsion is here, it is a viable option for a sailor, and if you are ready to enjoy it then there are many options, and people out there who will help you with the conversion. Cruising the bay as you have described is the perfect use for electric propulsion and if you want to increase range you can always carry a small, portable generator (see Capt. Mike's blog above).
Good luck - if you do decide to convert to electric, you will be happy you did. It makes being on the water even more enjoyable.