When it's blowing above about 20kts. here on my lake, I'll put my Hobie 14 sail on my Prindle 18. The mast has a halyard cleat at the base, so I tie off the halyard there, the top of the sail is about 3' short of the mast head/hook. I can still downhaul it pretty flat. I also have a rolling jib on the Prindle 18, so I can use it downwind, and roll it up for upwind, if it's too windy. I'm almost always sailing it solo, so that's nice to have. Works great up to about 30kts. but that's on a flat water inland lake.

I wouldn't want to be out in the big ocean on a small cat in 30kts, even with a reefed sail, due to the wave action. Going downwind in those will flip you without any sail up at all!

I agree with Karl's sentiments above.