This is pretty airtight
It doesn’t freeze the player, and doesn’t check for overlap on close, but you get the idea.
The only problem I have with this ‘overlap and press a key’ method ( which I assume is all over youtube ), is you can face away from the door and open it with your butt 
Reading your description again, you want it to close when you get off the box. This is fiddly if you have long open and close sounds, because you’ll end up player multiple copies of them.
I will modify this to close the door when you’re not on the box, but only after it’s finished opening. ( there are so many possibilities ).