I'd say go with the idea about carrying two for different needs. I'd add that if white water, even mild ww, will be encountered, then take one WW paddle and one power paddle. The spooned power paddle - even a wing - will be nice on easy strecthes where you can make good time. The flatter and more simple WW paddle will make braces and sweep turns and even rolls easier on the rough stretches.

As an additional tip: if long stretches of unprotected water will be covered, where strong steady winds are a problem - head or following - then make that power paddle both feathered and unfeathered, ie. take a two-piece that you can vary. It is also a life-saver if you develop that wrist pain since zero feather will help.

good luck, that trip is a long one!