When I was in undergrad, I flew R/c aircraft and we would have x/c events where competitors would pile into the back of pickup trucks and fly as many planes as we had channels (analog radios) to see who could go farthest. As I recall, the best we ever saw was about 90 mi by a guy with what amounted to a motor glider.
at the same time, the smart guys in the engineering school broke the world record for R/C airplane altitude by achieving something over 38,000 ft. It was limited by transmitter power only. (Was still climbing 1000 ft/min+ when they lost control authority IIRC)
That was 30 yrs ago with glow plug engines burning nitromethanol lubricated with castor oil. Pretty sure the Uni engineering wonks are WAAY past that now in the era of cheap gps and semi-autonomous control.