This is funny. It turns out that Tommy Collins, much like myself, was a very versatile guy. He could do a lot of things and do them well. Did you know that besides being an ROTC guy, he was an actor? That's right, back at Woodrow Wilson high school in Dallas, he starred in a one-act play.
Ah, Radio! One of my all-time favorites among one-act plays. And he played Ted Connally, no less; a very irascible character. I'm sure Tommy wasn't that way in real life. But now, let's make the comparison to our ROTC guy with the signature of Tommy Collins over him:
Bingo! That's a match. He was 3 years older on the right. 1929 vs 1932.
But that means that the figure with the name Tommy Collins written on the ROTC photo was indeed Tommy Collins, and the only one left to be James Bookhout is the short chubby guy in the center. And he went on to become the Garage Shooter of Lee Harvey Oswald.