RSwank and Stig,
Thank you both for your contributions, and my apologies for a very dilatory response! I have been and still am busy writing. Unfortunately, this has proved a very difficult subject to research, so I will not be including it in my current draft. Let's keep thinking about this, I am sure there has to be a list of rally participants somewhere! If nothing else, foreign military attaches would have observed closely.
Dornier 23s participated in the 1936 Nuremberg rally:
https://wartimeline.com/luftflotte-l...1-default.html
https://wartimeline.com/14103-thickb...lt/default.jpg
Dornier 17s participated in 1938:
https://www.gettyimages.co.uk/detail...-photo/3071556
Heinkel 111s flew over Berlin for Hitler's birthday on 20 April 1939
https://www.alamy.com/stock-photo-lu...170543747.html
Kind regards,
Dan