I'm going to go totally against the grain on this one, and suggest a skin-on-frame kayak. Your parameters for use are pretty impossible, and I can only think of one kayak that is small enough to get around on a river, and super sea-worthy for a trip on Lake Superior. Brian Schulz's F1. Skin-on-frame kayaks are not fragile- they're quite tough, and they're faster, less toxic, and much less expensive to build than a strip or S&G kayak. In fact- you can take one of Brian's classes and build one with him for about the cost of building a strip kayak. Just something to think about.

m

http://www.capefalconkayak.com/f1.html