And what percentage of the above would actually prepare a student to thrive at any STEM subject at, say, MIT, as an incoming freshman?
Unknown. I think background in rocketry and motor repair is already what goes on applications for admission to such places i.e. a well rounded skill set is considered a good hand. Say your rocket group got a projectile all the way to 50% less atmosphere and was able to aim and gain exposures of tiny astronomical objects while in flight. That's what the big boy and girl astronomers do today with their modified 747. I think an HR person checking a resume would necessarily draw a frowny face.