As the greenhouses are the same size, we are going to join the two greenhouses together and glaze the two with polycarbonate. The plan is to join the back of Paul's greenhouse to the front of mine and remove the cross members that only support glass. Then the front of Paul's greenhouse provides a working door. This will leave us a Crystal Palace style greenhouse still only six feet wide but now eighteen feet long and seven feet high.
What could possibly go wrong? I'll let you know how we get on.