Can't you just use a Pokémon with the Magnet Pull ability? Aron is part Steel type, after all. Granted, you won't be able to Synchronize, but it does make it easier.I'm up to at least one shiny a day. I've given up on trying to horde encounter a shiny aron though. It's encounter rate is to low for such an opportunity.
I did, however find a shiny ekans in a horde today. Nice little green snake.
I personally find Ekans to be much more annoying to encounter.
That would make the durant easier to find as well and they're the reason its so hard.