Not sure this will help or hinder. I have taken my son(s) to a spot (close to the security parameter, that permits us to view take-offs and landings at St. Louis International. A cop drove by once, and a airport cop drove by about an hour later (probaly not related). What they saw was a couple of kids and a adult sitting on the tailgate of a pick-up truck, with binoculars and a camera on a tripod (nothing fancy) on a Saturday Afternoon.
Not saying you should have a couple of kids with you, but, if looks like you are engaged in a hobby to the casual observer the cops are likely to not bug you. Tripod with camera mounted and a folding chair for the slow time may indicate to a cop nothing more that a dude with too much time on his hands.
A cop may not even see your OCed pistol. If a cop sees your OCed pistol he may not care. Let us know how things work out for ya.
Just a suggestion.