That's one of the great thigs about building your own boat. You can put any cockpit in it that you want to. I'm building by Guillemot with a cockpit that matches the Valley Canoe Products "small" cockpit. That way I can use the same skirt as on my Pintail. It's pretty quick and easy to trace the outline of a cockpit off an existing boat.

My first two boats were from CLC kits.(Cape Charles 17 & Patuxent 17.5) I found that Perception makes an all-neophrene skirt that fits nicely. It has some adjustment to the rim shock cord. There are also straps to adjust the waist to get a good fit around the paddler. I suspect that the Chespeake rim is about the same size