The railing has specifically been identified as "Common"; they don't even allow flower boxes on the inside of the railing.
I was told by someone on the board that other units in our building had dishes, but a walk-around disproved that; it may have been in the past, and they likely had bucket or tripod mounts. We only have the one building, 42 units.
I am going to ask about mounting on the wall, as my understanding is that the walls of the balcony are "limited common", exclusive to our use. Plus there are already a few small screws in anchors mounted in the mortar. (The dish would have to be mounted with anchors drilled into the brick, if I go that route, due to the load.)
Hope that is a solution!