I have a Tohatsu 9.9
Which a few of the boatyard pundits said was too powerful for the C22.
I gotta say that this is a terrific engine, powerful enough to get out of the way of anything I need to get out of the way of, I could probably give a fellow sailor a tow and at low RPM it seems to sip gas.
I got it reconditioned for $600. It's a two stroke from the late '80's.
I would think a 6hp might work OK, but a 4 might leave you wanting when you need it most.