Sounds like a worthy idea, from the bloke who's full of ideas, at the best of times!
My opinion is to not be too restrictive on the entrants. It's not 1919 any more, it's 2019 and the only thing we need to keep uppermost in the race rules is advances and improvements in "aviation technology".
Set up race classes (just like car racing), and offer rewards for lightest aircraft, electric aircraft, hybrid aircraft, conventional aircraft showing tehcnological improvements, etc., etc.
And of course, large Dick Smith advertising decals on every aircraft, would be a basic requirement!
