The kiteboogie: keep your tush 7 inches off the ground and go way too fast

Step 5 How long are you?

Now is a good time to get dimensions for the cart body. Sit on the edge of a plywood piece and see how far out the tips of your toes are, with your legs straight. Measure that distance. I'm about 3.5' from my butt to my toes. Take about .5' off that distance, and that's a good spot for your steering column. Measure off that distance and mark it on your plywood.

Leave about 6" beyond where you'll put the steering column and then trim off the plywood beyond that point.
If you like, you can taper off the car body--leave a width of 6" or so at the tip for the steering column, but feel free to make whatever shape you want, as long as it'll be comfy to sit on.

woohoo! You have a body!