Mark _australia said...I reckon....
slalom with 2km reaches, at 90deg to wind.
out n back 25 times.
3 classes:
Open - race / slalom gear
Novice - race / slalom gear
Have a bash - anyone on FSW or wave gear

I reckon your either in for the race of a lifetime or your back on the milk pond (aka the retirement village of windsurfing)
I didnt ask for your opinion about 90 degree sailing, this is a classic 100km DOWNWIND race on smooth protected water that would potentially attract many from around the world and not for the feint hearted.
I would love to see you gybe 48 times on a 50km marathon, could be entertaining

The categories you suggest sound like something to work with