Oh dear, that's too bad. I'm terrible at judging sizes (this is my only snake so I'm very much still learning). I looked at the site just now and definitely misread. The medium boxes are recommended for BPs up to 700 grams (his last weigh in was barely 400) while the ones I got are for full adults. Oops.
He needs new hides because I started out with the log tunnel types. I know hides are best with one entrance so they're shoved up against the tank wall, and the walls have black foam board over them on the outside so it's perfectly dark for him. But he's gotten too big and both barely fits in them anymore and is too strong to where the logs constantly get moved away from the wall just by his movement, so the "one entrance security" aspect gets ruined. He doesn't seem too bothered by it but I'd imagine he'd prefer to have a hide where he's not sticking out of both ends like a hot dog too big for its bun.
So I'm guessing I need to get a couple of the medium hides then?