Guys, I appreciate the suggestions and I have searched the site - what is needed are elegant solutions that will function for a service team using the vehicle in a professional environment.
I can't send my team to a job site and have them whip out a chain and throw it around a lamp post and say - ok our $155,000 machine shop is now secure. Plus the $50,000 in American Made hand tools in the back - no worries. You get the picture, I want and I bet others want to find - Freightliner, Snap-on, Matco grade solutions.
I put a deadbolt in an M35 door. I considered it secure as a 'lock' because it would have taken a big crowbar to force the door open.
http://bunkerofdoom.com/mil/m35/lock/index.html
It's not a pretty job but you can have a machinist improve the design for you.
If you want a whole vehicle solution, then you must combine several systems at different levels. If you don't know how, try looking up vehicle security companies that handle costly vehicles.
1. if alarms do not use 24 volts, then you should put in a 24/12 volt converter to keep a separate 12v car battery charged. secure the battery in a box with a lock. Make the alarm power source separate from the starting batteries and inaccessible or hidden. put the alarm brain in there. Use a wireless alarm that informs your crew members, all of them, that the alarm has gone off and has not been properly disarmed. Today these things can even send text messages ans e-mails. The alarm also needs a siren.. as usual. but it is the enhancements that matter. You have to put a door switch on every hatch that allows access into the truck. Use passive IR motion sensors on the outside, to make it chirp when someone approaches. add a vibration sensor to detect noises caused by someone breaking in. Put deadbolts on all the access doors. It doesn't matter how much money you have or what the goods cost. Aside from keeping a hungry crocodile inside the van when unattended, there is only so much you can do. The true experts in vehicle security and protection system integration probably won't be found here on this board.
2. track it. There is a product called skylink you can get at any Ford dealer, or online. It is a combination cellphone and GPS. It does need to see the sky.. but it has very good coverage for the cellphone part. You can pay each month to have a web interface where you can see the vehicle location at all times. You can set boundaries for it, etc. It is only $700-900. No monthly fee unless you want the web interface. Normally users call the 800 number when their vehicle is stolen.
3. buy a commercial tracking system like 18 wheelers have. add that to the pot.
if it is unattended and there is no employee available to fend off burglars or call police, then thre is nothing you can do except maker it hard to break into.
