Actually, inflatables -- ones designed for whitewater -- are far more forgiving than hard-shell open canoes.  But you have to know how to read and run whitewater. These are skills you have to learn.  I would not want to have my first tandem run in a boat I'd never paddled before on an Alaskan river I'd never paddled before with a partner I'd never with (and who might have close to zero experience), wearing only splash gear.

BTW access to the Kongakut is via small plane.  Hard to carry rigid canoes.