The Roll Bar Brace sits between the top of the Roll Bar and the top of the Baggage Bulkhead. I could not rivet down from the top without steps, so decided to roll the fuselage on its side. Other folk had done this, but I had resisted doing so, because the fuselage still has a number of clecoes. I finally decided the structure was rigid enough so the clecoes could come out. It was then easy to roll the fuselage on its side. I wish I had done this ages ago, as it would have made the installation of the plumbing etc. a lot easier.
Picture 1 show the Roll Bar Brace riveted on (on its side). Again no issue getting the rivets inserted through the thick Roll Bar material.
Pictures 2 and 3 just show how much easier the plumbing might have been! They are top views of the plumbing taken with the fuselage on its side.