Hi
@Dogbowl first of all, have a great trip.
I have done several LOBs before and I agree with what the others have said. While at port, it is wise not to put anything out that may prove "tempting" to the locals. Even if your boat has security cameras, that will only help to identify someone after you notice something is missing which might be after you have departed the dock. Easiest solution is to wait till you leave the dock to put out your valuable stuff such as dive computers and camera gear.
Theft after you leave the dock is extremely unlikely since the thief will have no place to go after the event. In fact, most (if not all) LOBs that I have been on do not even have locks on the cabin doors. Once you leave the dock, feel safe in putting your dive computer with your other dive gear at your assigned station and to assemble your camera set-up and leave it on the camera table. The one caveat to that is that if it is really rough, you may want to keep your camera where it won't fall off a rocking table.
Having said that, I will always take something small that I can put valuables such as my wallet (and cash/credit cards/ID), my passport and my travel info in. Not only does this remove temptation (out of sight out of mind), but if something happens, then everything important is in one place. I can grab it on my way to the muster station. For this, I typically use a
Pelican 1120 case with one of my luggage locks.
Gear mix ups, however are quite common and are almost always a result of honest mistakes. Get any of the waterproof markers mentioned above and put your initials on your wetsuit and any gear that you feel may get accidentally grabbed by the wrong person. (Bring the marker with you just in case you need to mark something or to refresh things that you had already marked.)