I did consider that, in fact I did it with my African Queen (the Billings kit) years ago.
It would save a lot of swearing, and a lot of expenditure, you're right...the more I delve into this, the more nervous my bank manager becomes. Another thing I've considered is to power it conventionally with an electric motor, and then hide everything in a wooden engine cover, with the engine controls fitted. With a bit of care, and with micro electronics, I reckon I could make a half decent open boat out of this.