This is a great point that I didn't even consider. I got 27 laps on Toro in 2014 (throughout the year) and 95% of those rides I saw at least one walk of shame while waiting to board.
I've never had experience on El Toro where someone had to leave the ride because of his/hers build. In my opinion, Batman: The Ride is a pretty restrictive ride, even for me. Last season I saw about 4 people on one train get denied.
My father is a pretty large dude, but he made it just fine on El Toro and Batman. I think it varies on the way the person is sitting.