So you have to sign something that says you won't drink alcohol while there, but it's okay to fire up a big old doobie (you know, since it's legal there)?
We've camped in MI state parks multiple times. It has been a few years back so unless things have changed, keep it out of sight, and don't get hammered and get stupid and you'll be fine.
Edit: Don't forget about your empties. Keep them out of sight too.