Hmm
Jim Boyer will be in the Annapolis /West River area in about a week or so, perhaps you should get in touch with him for direct answers to your questions. There is also a dealer who can get you a boat.
What you are looking for may be rare on the used market right now. Three boats would meet your needs, the Nacra, I17, the Hobie FX one and the Taipan 16. The latter two can be rigged with jibs alone, spin's alone or both. I know of sailors who sail all three of the boats on the Chesapeake Bay and each loves their choice. The old adage of you get what you pay for holds for cats as well.
Of the older boats... I would suggest that the Nacra 5.5 uni would be a better choice then the Hobie 17 since the 5.5 is also used for the 5.5 sloop and will carry 300 lbs pretty well. These boats have been succesfully modified with Hooters and now certainly with snuffable chutes when you want more horsepower down wind.
Good Luck
Take Care
Mark Schneider
CRAC