If you already have the single motors, and need to join them, maybe you will be interested in these people's work:
http://sonicracingaustralia.com/enginemounts.htm
Mart pointed them out to me.
Mart,
I do like your suggestions, and please keep them coming!
The idea of opening the hatch up from the back is interesting, but the system should permit quick release too, in order to enable me to work in the boat...
Will put my thinking cap on this and see what comes up.
At the moment I am trying to study amechanism that should enable me to servo-trim the new RCMK Arneson drives...