C.S.
Since it sounds like he's got the idea, you should go ahead and have him try it at night. The biggest thing is that for night you probably want to remove the crib from the room, because otherwise he might be confused. I moved my oldest (15 mths at the time) for the same reason, and the first 3 nights were rough, and then it was all good. =)
Having a gate, or the door closed so he can't open it, is probably good. You might find him asleep on the floor sometimes or whatever he may do.. it's all pretty normal.. but they get the hang of it pretty fast.
Good luck to you and your big boy!