So, it's completely possible to turn green tomatoes red. Just get a brown paper bag and put them in a dark place (like a closet) and wait. I checked on them a couple of times, and then today, found them all completely red. (Yes, the numbers don't match (if you count the green above to the bottom below. I ended up adding a few more tomatoes to the bag after taking the original picture).
I'm impressed. And now I need to find something to do with all these ripe tomatoes!