I agree with the challenge concept. I advise requiring accurate aircraft fuel windows for each leg of any Challenge. I'd also suggest using downloaded RW Weather, and certainly a pledge of no Autopilot.
That's quite similar to the "Around The world In Eighty Days" challenge held a few years ago on a different site than this. The object of which was to visit all of the locales visited by Phinias Phog in the book. However the choice of vehicle, as long as it was a known sim vehicle such as aircraft, ship, train, etc. was allowed. And yes, most of us changed "Horses For Courses" along the trip. We started out with several hundred entries and ended up with a very small percentage of finishers.