agree...and a small dog that will take your hand off also works! With many months on the road in Mexico and Central America I never once had a problem, a lot of that due to my dog. I also put signs in the windows in englisha nd spanish that say beware of dog.
To take a dog with you on a trip like this though takes special preperation and also consideration for the dog as you travel.
The locks look solid, seen them used before. Thing is most people are just going to toss a brick through the window and climb in. At that point the lock is useless. Tinting windows helps a lot, obviously to reduce what people can see in the truck but also because they will be harder to break.
Just don't leave anything out in sight, use a steering wheel lock, a good one and you will be fine. If you make things available to thieves they will steal them. For vehicle security you cans imply pull the coil wire or better yet install a valve in your fuel line you can turn off. Turn off the fuel line when you park it. If somebody starts the truck they will get 100ft and it will die so they will think it is a problem with the truck. Cleaver security measures work better then brute force.
Being an old 40 series I don't think you will have many problems unless you leave stuff out in plain sight. You are going to be low key in that truck, much more so then a lot of people who do these trips. Lock boxes for the cargo area are a go though too.
Oh and in case it has not been mentioned, make sure you have the orange triangle and fire extingusher. Required by law in some countries and used as a way to bribe you by the cops. Not to mention how much fun it is when the cop with a huge gold tooth smile asks to see it thinking he is getting $50 and you turn that smile into a frown when he sees you have them!