Thanks for your response - the short answer is no, I haven't done much more. Apart from getting a quote from a local (S. Germany) for a custom cockpit tent for our BRe, which was in the order of €3.5k, and I decided to put the funds towards buying a BC23 (see for sale/wanted section).
So the opportunity still remains!
Regards,
David
PS I should add that I did contact Advanced Covers for a quote, but they said they needed to have the boat in their workshop which was not practical for us. The local quote I had was for a design like Michael's.