Less than 5 seconds to get through. That chain says don't snap me so a thief will to find out what the owner wants to protect and snap it.
The best security is a combination of actions.
Don't leave valuables in sight to attract a thief. With all that solar on the roof, the thief probably already knows that you have stuff, but don't leave bait out anyway.
Be aware where you are leaving your vehicle. Don't leave it unattended where nobody is around. That is asking for trouble. When you do leave it make sure it's in a place where there is plenty of foot traffic.
You want to force the thief to have to make noise to get in. So fix any known weaknesses in the locking mechanisms; example the Ford Econoline factory lock housing suck, secure them. Force the thief to break a window to make noise and cause commotion. Have an alarm to make even more noise. The alarm should disable the vehicle ability to start.
Valuables hidden. After the thief realizes that he or she can't drive it away, they should only be able to grab something quick with the noise and commotion, so they will take something in sight that is not overly valuable.
As tempting as it may be, don't leave your dog in there.
Since the dog is not in the vehicle, consider having your alarm notifies you so that if someone breaks in you can come running to make the thief wish it was a dog and not a jealous owner.
Be safe out there.