It wouldn't take a lot of knocking. It looks like what they call a 'temporary structure'.
I haveno problem with the concept of a speactators' area, there's one at Birmingham which makes a nice place to take a break if you're early for your flight. I'm not sure about one that is a long way from the terminal with very little parking.
I'm also not sure about having dozens of pairs of binoculars trained on me as I go through a check out and start up drill in a piper.
Spotters: Oooh look, he's forgotten the fuel tester and now he's got to climb back in to get it.
Me: Doh!
Spotters: Now he's checking the oil and hasn't brought anything to wipe the dipstick with
Me: Aaaargh!
Spotters: He's wiping his hands on his jeans. Eeeew.
Could we have a privacy fence please.