I figured out how to beat auto-fill.
When auto-fill was first permanently turned on, I loved it. Queue times got incredible short and I'd only get support a very small fraction of the time. It was good. Until I guess everyone kinda realized that this was permanent and dodge rates went up dramatically. Auto-fill stopped being fun because every third game I always ended up playing support because auto-fill immunity only lasts for 2 games.
It took me a while to catch on but what seems to happen is that when I get my role and someone dodges, it would usually be someone who was auto-filled and didn't want to play what they were given and I'd be there replacement.
The way to get around this is to stop the queue when someone dodges. Give it a couple seconds so these players are matched up in a different lobby and queue up again so you get matched with a different group. Your chances of not auto-filling goes up dramatically.
Hope this helps. GL