Thank you for all of the excellent replies. It seems I cannot go wrong with either the 17 or the 20. I have a rental shop that I use for many purposes, It is roughly 24 x 20, but the catch is that the 10' wide door is in the middle of the 25' side. I need to make sure my boat can get out. Some measuring and some time at the drafting table should yield my answer.
Weather is not a problem, in fact in the summer I use the high temperature epoxy curing technique, close the door and bake your boat at about 120F!
I will follow in this forum and see what else comes up. I will keep you posted on my progress. I was glad to see a forum for B&B designs. I was going to build a Sharpie until I saw the Core Sound designs.
I will order plans soon, are the spars built by the users, available from somewhere, wooden?, Aluminum?
I probably should read all of the posts I am sure all this is covered somewhere.
Thanks again for all of the information.