Geelong is actually majority Geelong supporters though. Is there any council in Melbourne where a majority of footy supporters are St Kilda fans? You'd probably be struggling to find one with even a quarter.
The only way you'd get it done is if you had 4 or 5 clubs sign up to play a few home games a year there. Which would obviously be tough.
I would have thought the saints fans are overwhelmingly from this part of Melbourne....whether or not say Kingston or Glen Eira are 25% St Kilda, there would be large numbers in those areas and maybe down into Frankston