It doesn't have to overhand the railing. The dish can be mounted on the interior of the railing. There is an actual railing mount with adjustable slides and dedicated bolts for the mast but I can't find a pic. Another way is to get 2 fascia plates and sandwich the rails while bolting the mast to those. The purpose designed railing mount is pretty new.
So this mount prevents ANY part of the dish from extending past the railing? I'd love to see a link for it when you can find one. I've got some customers that would appreciate it, too.
Sandwiching the rails with the foot plates will cause the dish to overhang the balcony in one way or another.