I've seen a lot of OBs mounted on sailboats, that were basically live a boards. (its cheap housing in an otherwise expensive location)
a honda 25 with the extra long shaft and a low pitch prop would work, in flat water, and to move around the bay. it has remote controls, and good selection of props.
The problem as many mentioned is in a short choppy sea. Like when entering or exiting a narrow channel.
As long as the boat stays on the 'inside' she will be Ok. (I'd get the unlimited tow from boats us, for ~150 /yr.).
you can also get a jacking plate with hydraulics that will help get the engine out of the water. my guess is all in $4-5k for an outboard with controls and jack plate.
I would imagine the boat is only worth a little over the cost of the ob setup...