Good suggestion with the Tiki 21. The setup time is the killer though. Any non folding tri or wider than a tilt trailer setup is pretty much out for me as I'd like to sail rather than rig. I think something like an 18 square with freeboard would be about right. Uni rig, light (enough), spin for offwind stuff, simple setup. Keeping it to 8'6" would be even better.
Going to the way back files, a lighter and smaller version of the hard decked 19' Pacific cat would be a great general purpose daysailor and camp cruiser. Foam core would go a long way toward making the hard deck **** area light enough, alhtough a tramp might be just as good solo. My 18's tramp is fine for two since the arched beams means my buddy won't end up in my face in the morning. However, the 18 is HEAVY. Adding freeboard to it wouldn't help much either in the weight department. In fact, my double Tamanu is a better cruising ride after doing it back to back in '08 on the TheMightyHobie18 and '09 on the Double tamanu hulled TheMightyHobie18 rigged cat.
But a 20x8'6" boat that weighs 400# is way more than I need solo...thus this thread. The Hobie AI or TI are close in tri form if a bit slow. Is there anything in cat form that springs to mind?
Dan