I have a Bell NorthStar (16'6" x 34") that's been used as a solo BW tripper twice.  It works great.  I mounted a seat about 18" behind the center thwart and removed the bow and stern seats.  When paddling, I shift my weight to the side I'm paddling on, which heels the boat and makes it more responsive to control strokes, something I do in my solo boats all the time.

The Spirit II has a little rocker - not much - and leaning it will greatly improve its maneuverability.  The more you lean, the more responsive it will be.