Ah... somebody with a fair bit of racing experience looking for a class that focuses on a certain niche.... very different then the casual guy looking for the right boat.

You obviously have some thoughts on the kind of racing that you want to get involved in. It sounds like you prefer the distance race format over buoys.

Your options for distance racing will be limited if you go with a single handed class. There is not that much interest among the single handed racers for those epic journey type races. Safety is an issue for both you and the organizing authority.

Almost all distance races are scored on handicap since fleet size is problematic. Some races that would be of interest and are close to you are:
Red Fox regatta in Michigan contact Cram
A Canadian Distance Race in Ontario, contact Pitchpole Dave
The New England 100 in Naragansat Bay, contact Rick Bliss
The Statue of Liberty Race at Sandy Hook Bay Catamaran Club.
The Storm Trysail Annapolis to Hampen, contact CRAC
The Annapolis to Oxford and the Race Back Contact CRAC
The Version 2.7 race Contact Fleet 32 in Va Beach
Ohio has a distance race of 20 miles at Put in Bay
The major Florida Distance Races, (SteepleChase, Miami to key Largo, Hogsbreath 100 and the River Race) The Macho man in Tampa plus a big distance races in the Panhandle/Fort Walton and a couple of shorter races on the east coast of Florida.
Of course the Tybee 500 and the Great Texas races are limited to two man teams...
Make sure you can play single handed in the events that interest you.

If you are interested in Line Honors/ first to finish... Consider the Marstrom 20... Only 2 boats in the US but it's the fastest boat we have here.

If you want distance races coupled with the chance for a large sub class... Get a Nacra 20. (and they are good for a couple of buoys race turnouts a year including NA's, Trade winds, Spring Fever and two events on the Chesapeake (not including the Wisconsin fleet),

If you want distance races coupled with a project to recruit the larger number of buoy's racers on F18's to the cause of doing distance races... go with an F18. Your crystal ball will be needed to forecast the fleet interest/growth in the next 3 years.

If you want a two man buoy racer you should pick the F18 It is a national class with large fleets in Canada and upstate New York and a growing fleet in New England.

If you want a strong single handed class, the A class is national compared to the F17 or F16 which are regional classes. A Michigan fleet is now up to 5-6 boats with a very strong fleet in Bristol RI. Get a hold of Steve Clark for advice, he is your size and has sailed and built several A class boats.

If you want a spin single hander, the F16 would allow your sailmaker to build sails to your weight but the class racing is spotty.. the F17 class would be a lot closer to you and they have a stronger class schedule in CRAM, Ohio and the Panhandle.

At 230 pounds... unless you have a strong 120 lb crew lined up with the same interest in going racing.... you are best off looking at one of the two 20's. I would look to get in a race on all of them if possible to narrow your choice.

Have fun!