RE-E-Power has been making some neat electric "pods" for sailboats and power boats. They are a small outfit, but seem to have some nice designs and are willing to work with you.
Pods come in a variety of sizes and configurations. "Sailboat" pods have the prop on the front (protected by the keel/skeg), while powerboat pods have the prop on the back so that the unit provides its own skeg protection.
Check the videos (captions provided by the company):
RE-E-POWER’s dual E-POD System 3000-PB dry test demo:
First run of the E-POD 3000 motor after installation on a 30 foot sailboat.
Testing the E-POD System 3000 at the dock. Drawing about 15 amps at 48 volts. This is just above neutral power and is obviously not a toy! We couldn’t run it higher at the dock because it was banging other boats around.