I second all that Paul says.

I am one of the guys here that make models first ( after Paul's suggestion ), and if you're experimenting I can not emphasize how interesting, useful and fun it is! For the simple models I made, it takes less than an evening and will not cease to be useful to you.

The method I used was 1/4 scale, forms out of doorskin ply(luan?), strongback out of a cedar strip, and iron on(heat shrinking) model airplane fabric for the skin. Paint if you want.

Because you will be stretching your kayak, I would suggest that there is scope for some form spacing experimentation here. I would build as above, but make the forms tight on the strip strongback, and pull a temporary covering of a leg of a pair of your favourite black tights ( you know the pair in the back closet next to your high heels and wig! - like mine!). Pull very tight and tie off with a twist tie. Observe for a while. Remove tights (on the yak!) and move the end sectional forms closer to the ends. Put the covering back on and observe. Play with keeping cockpit forms exactly where they originally were and only stretching the spacing at the ends. I think you could have fun here. For your model, use a scale of 1/5 or 1/6 i.e. 3 feet long of more. Sounds much too big, but the smaller sizes just make a toy not a tool and trust me you will never, never, never regret the size. I would actually make it at 1/4 scale like surfyak.

When you're sure, glue the forms in place and measure their location. Take some time observing so that you don't have any untoward high or low spots.

Other points - If you move the forms symmetrically in the front and back, the cockpit placement should be pretty well as originally designed. The scale displacement of a 1/10 scale model will be 1/1000 of the original - 200 lbs to .2 lbs.

Any way if you do decide to make this model it will look something like below

-mick