Wow.
So, hi Nick and welcome. Despite the instant and rude response from one, you would be very welcome at our little reunion.
There is a Swiss glassair that participated for many years, a young French couple that came over in a doorless two seat aircraft that looked very much like an ultralight, and a whole flock of South African aircraft that came en mass. Most recently there was a fellow that did an around the world flight in a kitfox, I believe, timed to be in Oshkosh for the convention. John Johanson has flown around the world twice out of New Zealand, once eastbound and the other westbound, each time stopping at the convention. That's a different class of aircraft, but a good example, as is the German canard, a Defiant, I think, that made the trip at least once.
There were articles written in our magazine on all these adventures, and they should all be available through our headquarters and publications department. That should give you a good start, and I would imagine any of the folks who have gone before would be happy to share what they've learned.
ICAO controls the aviation guidance on the topic, and Document 007 is the primary source for pilots. It is mostly about air carrier operations in the flight levels, but also addresses other options. It can be found at:
https://ops.group/blog/wp-content/up...-2-Amd-0-1.pdf
The host website, Ops Group, is also a good source of current information on global operations and difficulties / outages, so you might consider them as a source for realtime and near - realtime information for your route.
The routing you would end up with would be one of the Blue Spruce routes, which adds an historic element, as these were developed as ferry routes during the second world war.
Do you research and planning carefully, and have a blast!