Back then, ATC were a little more relaxed. “Was that a bird? I dunno. It just popped up and then disappeared. Strange” could have been what was said. Now, any blip is a phone call upstairs. Radar is a lot more accurate and ATC have the nerves. A balloon, a rocket, someone’s potato gun, anything that hits airspace on radar is going to be investigated, at minimum. More than likely, for small hobby rockets, you’ll get away with it or maybe talk to a local law enforcement officer but fly anything large enough, you’ll get a visit from the G men.
As I said, we were behind mountains. Not to hide from the radars but to find a sufficiently large open space that we could be confident everything would fall in said open space and flat enough we could pursue rockets without worrying about being inhibited by the terrain. And with vegetation sparse enough that if something did catch fire it couldn't spread.
