Seen YouTube lately? Scores of kids are sending balloons and other devices into space (close enough anyway) and back again... Then go and find their "aircraft" with GoPro fitted via Satellite tracking. Impressive what you can do these days for a few hundred dollars. You'd only have to fit an extra battery pack to get to 8k even on a cheap model. I have a $60 one that would get to 3,000 ft easily on a single 3.8 volt batt.