I dunno. It seems like you'd probably have problems with expansion of the gas if you're going from 0 meters ASL to 2000 meters ASL.
Keep 1 or 2 shots worth of gas in the mag (like you should be doing anyways) and fill the rest when you get there.
If you know anything about commercial air planes you'd know that the fuselage actually expands slightly when you're up in the air and those can take a lot of stress.
Now scaling that down to a gas mag... I'd be careful. It's not like it's going to randomly explode but chances are it wasn't manufactured to go from Sea level to 50,000 ft ASL, most likely it was manufactured to more realistic tolerances based on "normal usage" eg. Sea Level to a few thousand feet ASL.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE