I can't see the photos where I am, (yet) but it sounds like a good idea. I think you should try to source a two-stroke 5hp engine. The weight would be comparable, and you'll have more HP.
If you coordinate with winds and currents, hopefully this can get you through those narrow, unsailable areas of the ICW. I'm glad you came up with some kind of emergency propulsion.
S/V Old Shoes
1973 Pearson 30 #255