how bout a nice restored wooden Folkboat?
Pretty, been around a long time, can be found cheap if you're willing to put the work in, good sailors. I think some have no engines (some do) so an outboard on a bracket would be realistic.
Is this book set in the present? Then it's going to have to be a restored boat of some sort. The Ohio river? Don't tell them wood does poorly in fresh water, it could spoil the "romance".