It's good that you discovered that kayak design is not exactly rocket science. With all the computer design programs available today coupled with all the kayak experts you would think that all kayaks would be exactly the same.

If you took two pieces of plywood and pinched them together and spread the middle a little behind center and added a two piece bottom to it with a bit of rocker, you would have a pretty damm good paddling boat. Then you build another and refine it a bit to your liking. Then you get opinions. Then you refine a third build. You are now a kayak designer and expert.

My cynicism reflects all the wasted energy people use arguing over the best boat etc. It doesn't exist. Your boat looks great and if you want you can refine another one for another intended purpose.

The adantage of pre-existing plans is that you can hopefully try the boat or get opinions so you don't spend a winter building something that you are totally disappointed with.