Best Hull type?
Having had an evening to think about this, and having seen and been reminded of your earlier discussion about using plywood construction, I had a couple of additional thoughts to throw out here. From your description, I would suggest that there might be a few designs that you might want to investigate. The first would be the Cape Cod Cats. Cape Cod cats were designed for use in the frequently choppy waters around the Cape. They were meant to be be capable of withstanding a wide range of conditions. Most had a small cabin and large open cockpits which would be well suited to your goals but they were generally considered good boats. They sailed well in moderate winds and seas. While they are often cited as easy boats to sail, they could be a real handful in a stiff breeze. Like most beamy boats they did tend to build up enormous weather helm when heeled. They were centerboard boats and so you could play with the centerboard to ease weather helm a little, albeit at the price of greater leeway. While the Cape Cod cats had a comparatively comfortable motion for a boat that was that beamy, they still had a pretty quick and pretty rolly motion. Catboats have enormous sail areas and so their sails tend to be expensive and require a fair amount of effort to trim properly. Traditional Cape Cod cats were gaff rigs with an enormous single mainsail that extended well past the transom. As external ballast was added to Catboats, they began to use marconi rigs.
When I worked for yacht designer Charlie Wittholz in the early 1980''s, I got to work on some of his plywood catboat designs. I found that catboats were extremely hard to design well. If you study the lines of a tradtional Cape Cod cat they are surprisingly finely modeled in the water. Good plywood catboats are even harder to design well. Charlie was probably the best designer of plywood catboats. I would suggest that you take a look at his Madam Tirza design which is available from WoodenBoat Magazine pretty inexpensively.
These are comparatively easy boats to build. They are quite robust. The outboard rudder is reliable, as well as, cheap and easy to fabricate.
One thing about catboats (or any boat that beamy) is that they can be capsized and they do not come up once overturned. The rule of thumb in sailing a beamy boat in heavy air is ''never cleat the mainsheet. In other words Catboats are not idiot proof designs, but no wide beam, heavy boat is.
Another boat that you might look at were the Ellis designed Nonsuches. These were a rethinking of the Cape Cod catboat idea. Ellis did a brilliant job of mitigating many of the problems inherent in Cape Cod cats. The Nonsuch took the basic catboat hull form and narrowed it a little, raised the topsides, added a marconi mainsail on a freestanding spar, a fin keel and a counterbalanced rudder. This improved helm balance and windward performance, as well as, the ease of handling and increased the angle of positive stability quite a bit.
These were very nice boats all around. I suggest that you look at the Nonsuch 26. http://www.yachtworld.com/core/listing/pl_boat_detail.jsp?currency=USD&units=Feet&checked _boats=1300584&checked_boats=1355377&checked_boats =1289047&checked_boats=1303927&checked_boats=13927 01&checked_boats=1344118&checked_boats=1297454&che cked_boats=1266324&slim=quick&
The only problem that I have with Catboats for your intended purpose, even ones that are as well thought out as the Nonsuch 26''s, is that as catboats, they cannot be hove to and you lack a jib to use for balance in a breeze.
I do want to clarify that I am not literally suggesting that you build a Cape Cod Catboat, but I am suggesting that you look at the hullforms, especially the hard chined versions designed by Charlie Wittholz. I would suggest that you consider narrowing the beam slightly, adding a fully ballasted keel (I still suggest a long, moderately deep, fin keel for ease of handling in heavy air purposes.) I would suggest going to a fractional sloop rig with a large-ish mainsail. Lastly, for the purpose of keeping the hull weight low, (in order to improve motion comfort, carrying capacity, and seaworthiness) that you plank the topsides in rigid foam, and then cover that with a full depth epoxy/fiberglass laminate on the exterior (with a minimum of non-directional material to improve puncture resistance). If you used a deep section foam (perhaps 1 1/2" you would go a very long way towards achieving full floation. Coupling that with a series of watertight compartments you should be able to achieve full floatation.
I still think that wide beam-heavy boats tend to require more of a "highly energentic, consumate sailor", and in other words, tend to be pretty UN-forgiving as compared to more moderate designs which tend to be able to take care of themselves.
I need to finish lunch and get back to work, I hope that this is helpful.