Most of the thin crust recipes on this site are for thin and crispy crust. If you're just going for a really thin crust that's still kind of soft, I'd recommend starting off with a New York style dough. I like my crust a bit thicker, but one day when using a dough ball that had been in the refrigerator for about 48 hours, I accidentally let the dough ball get warmer than I usually do before shaping and it was almost like liquid when I stretched it. The result was a very large pizza that was very thin. Maybe doing something like that would be a good place to start.