Ditto on the question of locking in. I chose an RV latch for my side door for that very reason.
I like the slam latch in the first link, those things are brilliant. I installed one of those on my ramp door for that reason: To get out in a hurry if I need to.
Pic in the post just above center on this page:
http://www.tnttt.com/viewtopic.php?f=42&t=46134&start=30You can't see it well but there's a screw head the chain ring is hooked on that keeps the bolt retracted when not in use, like it isn't even there. At night I lock the ramp door levers so they can't be closed from outside amd release the ring from the screw so it's just feeding through the eye bolt. Then all I have to do is grab or slap that chain and the latch retracts and I can push the door down.

If I want out in a hurry, I want out right now.