Yeah, as I expected... no magic. Just brute force and ignorance.
I'm not nuts about the interior trim route, since one can't get at all the screws and I expect it'll be nasty to try to get one's arm in behind it to pull the latch rod. To boot, I've got a dog barrier in the back (making it a bigger PITA to get in there) and the spare is in the way of pulling the trim away from the door far enough to snake my hand in. Humph.
I discovered the exterior-trim-way-in at the junkyard - I was pretty impressed with the speed with which one can break in
by just popping it out with a pry bar, but (as pointed out) it's a destructive method.
What I'm thinking now is: Unbolt the license plate and use a 2" or 3" hole saw to install a convenient maintenance portal behind it - one that'll be covered up again once the plate is in place (with appropriate waterproofing, of course). And while I'm in there, I'm sorely tempted to add a little cable release or something to allow it to be unlatched from the inside.
Thoughts on these ideas?