I don't know about other eras, but my '99 had nothing except for the one "pinch catch" on the inside of the door (then you pulled on one of the dowel rods built into the outside of the door to open it). But that would sometimes come loose when driving, so the door would swing open, the light would come on, etc.
I noticed when looking at photos that some other Chinookers had added various exterior latches so they must have found the same issue. I figured I'd add something, but I didn't find anything super simple, because of how the door overlaps the opening, plus the shape of it, the fridge wall right next to it, etc. What I did was add another pinch catch further down on the inside of the door, so now there are two (I had a bunch of extras after removing some other doors) That has not come undone in a few thousand miles, and yet is not onerously hard to open when I want to.
This is what I mean; if your Chinook is like mine, there are plenty of these around. My closet had one; I added a second one.

- door catch.jpg (4.83 KiB) Viewed 5805 times
That doesn't solve your hole though, I realize! But I just mention it since it the hole may not have been a "Chinook job" (or it may be, if at some point in the timeline they added a real latch).
Edited to add: Hmm, I was looking for a photo of a closet door like mine, and happened to see this photo from another '99 Concourse showing a "box latch" inside. I'm guessing this was owner added, because in another photo of a later (2000) Concourse, it shows the same "pinch catch" as mine has. But figured it might help you anyway (I have no photo showing the hallway side).
On the other hand, the latch "pops up again" in a 2003. But there is ALSO a pinch catch. So who knows! Be interesting to see what others have. And if this "box catch" involves a round hole. Maybe it does, so you can operate it from the hallway side.
(BTW, meant to mention that I have not forgotten about the clock. I know where it is, but that "where it is" is a tub that's buried behind some other stuff, which I'm going to be moving relatively soon, at which point I'll unearth the clock.)