Gordon Boettger has made several long cross country flights in class A
airspace. Here's one:
https://www.onlinecontest.org/olc-3....l?dsId=5835349

Also a number of wave XC flights up and down the Owens Valley.
South of Bishop, they have a LOA to use the R2508 restricted area
https://www.edwards.af.mil/About/R-2508/
but to the north they fly with a clearance in class A.
Some of Dennis Tito's flights were like this:
https://www.onlinecontest.org/olc-3....t=olc&pi=45222

Tom