I have had a great solution for security when you must leave your van in
questionable areas, or are just too lazy to lock everything all the
time...Doggies..

  We have three Chesepeakes (a large aggressive breed similar to a Labrador,
but with 'evil looking' yellow eyes and a protective manner) and most times,
one (at least) is along when I drive the van.  I've tinted all the windows
quite dark for their comfort and I have a huge water bowl on the rear floor
if I have to be away for more than a few minutes.
   Nobody but NOBODY bothers the van, period!   I have some of those little
red brass signs on all four sides in the windows..'beware of the dog' and I
try to park where foot traffic isn't forced to pass close by the van, if I
am in town or a city..
  When I start a bike ride or a hike from an isolated trailhead, I don't
always lock the van if the doggies are along..Even in  L.A. I have no fear
that anyone will get inside..Of course, given that I live in the USA, if
someone did get stupid enough to open the door with 100 lbs of snarling dog
in his/her face, I would probably get sued and lose everything cause the
doggy savaged the crook.
  One time, at a deserted beach in 'urban' Baja, I was confronted by a
couple of pretty rough looking would-be crooks as I came back to my van
after checking the waves.  They were kinda 'checking me out' at like 5:30am,
probably wanting to rob me, so they asked me for a match and started sliding
nearer...I said "Match? Si, claro, en me auto" and pulled open the Van's
slider, letting Max and Jake out in their faces....They backed right off.
 I said "Aqui, sus phosphero?" (here, your match..) and they said..."Oh, we
forgot our cigarettes.." and split...
  For sure, dogs are a good deterrent to criminals and bears..even the
Mexican Army waves me right through their "Droga y Armas" check points when
they see the canine co-pilot in the right seat..
  Don Hanson
I make my dogs earn their food and health care by standing "guard duty"