How crazy would it be to design my own kayak?
I've been paddling a Great Auk (17’ 23”) for 5 years, smooth Southern Cal coastal waters, mostly point to point. Love it, good average speed, strong paddler (for an old guy).

What I would like to build next is a 20' 20" wide, swedeform, but not a surfski. I paddle hard. Last weekend I paddled into at least a 20-25 knot headwind, made steady progress for more than an hour, and could've done more but Palos Verdes was in the way. So I think whatever extra drag a 20'er might have won't be a problem. I'd go 22' and 18" but that's too far out there.
I’m hoping I can gain a full knot over my GreatAuk.

Plans--there don’t seem to be any that quite fit the bill. Maybe I missed something. Nick’s Mystery is clearly the closest option. (I don't need to follow race rules. What might the Mystery Pirate be like? 22' ? )

I've made a design with Kayakfoundry (but I had to turn in my PC) so now I'm fiddling with BearBoatSP on my Mac, or I can put the KFoundry files into a CAD app.
steep bow, swedeform 11' wide point, draft 4", steep stern.
I am willing to spend a couple of months and risk $1000 and wind up with a floating educational experience.
I can't see any serious downside except getting 1. non-optimal stability 2. a little too much drag (my Auk weighs 75 lbs--I don't think I could do that again if I replaced western cedar with bricks), 3. difficult to turn (I'm a rudder-boy anyway).
So my question is: Just how risky would it be to design my own boat?

Or just vote:
___ Go ahead, good luck
___ Quit worrying, just build the Mystery

Thanks for reading, and any advice.
Will