I met a couple at Overland Expo East who did extensive travel through Mexico. I noticed they had some security mods done to their truck, and we discussed them.
They indicated that (in Mexico) thieves commonly punch out the door lock, and open the doors with pliers. Or they just smash the windows.
This couple installed expanded steel mesh behind their rear windows, and a literal rod which prevented access to the door locks / handles. The front windows had 3M knockoff clear film which prevented the windows from shattering.
Their work was somewhat crude, but I think both could be implemented more elegantly if someone was very serious about security.
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