Andy,
here's the del prado "Bounty" converted to motor complete with pirate conversion overall (there's a pun in there somewhere).
A bit of planning at the build stage to enable motor and rudder set ups, and then some though as to how to gain access when, not if, things start going wrong. Getting some ballast slung under and allowance for a battery too.
Here she is, can be totally de-rigged in 4 minutes as I've used spring loaded masts and clip on shrouds etc. She is used by our local children as a have a go boat.

Kimosubby