Sorry you're dealing with this. Chances are the van used is probably stolen too. So tracking down any type of ownership info would be useless.
This is the MO for bike thieves. Have a van with a mattress in the back. Two guys to pick up the bike. Fast and somewhat stealthy as the van keeps the bike hidden.did they just lift and drop into the back of that van, or you aren't sure?
would a bulky security chain, tied around a pillar have helped?
I know the alarm systems you are talking about. I put in two of them from Airitronix called Scorpio. To me, it only kept the people not up to no good away from the bikes with the perimeter sensor. But in reality if the bike is being stolen, it only will give you a better head start in calling the cops. Because, frankly, what are you going to do if the alarm goes off and you see your bike actually being stolen? Confront them? That's a good recipe to escalating things and possibly getting hurt or worse being dead. You don't know if the thieves are packing. Now if you're packing, that still doesn't give you a legal ability to shoot the thieves depending on the state you live in.When I lived in Chicago I installed an alarm with a 2 way pager since a public garage was my only choice at the time. You can set it to only send you an alert if your bike is tampered with. Then set your pager next to your favorite rifle.