I agree not to give up on A&J. One thing you can do is take measurements of the width of enclosure you need. Then see if you can send the two side pieces down. Ask to make a new center section (match it up) as well as install zippers to fit the two pieces you send down. I believe it can be done by them, you've gone the extra mile to provide the dimensional drawing as well as the side piecesand will work out fine. They really try to work hard for you.
The other option is to find a local shop and have them come down to the boat to take measurements and fabricate a section. Really not hard to do, just need to get someone that wants to do a small job.