Glider pilots have completed two soaring safaris from Marfa (near the
Mexico-US border in the mountains of southwest Texas) north to Canada
along the Rockies, so that route is established as very soarable.
Perhaps a "relay" with different pilots soaring smaller segments of a
longer route. They could pass on a flag or glider-mail.
Burt
Marfa Gliders, west Texas
www.flygliders.com