For a quick and inexpensive cure, I mounted regular gate latches on the inside. They are the type that have a sliding bolt that enters a slotted receiver, then you turn the bolt to secure it. The end of the bolt has a hole in that could receive a padlock if you wanted extra security. They came from Home Depo, and solve the rear door issue with the plastic lock holder. It's a small pain to latch from the inside, but when leaving the van for long periods it adds a lot of security. I also put one on the side doors. That leaves the issue of someone smashing the drivers and passengers side windows, but some security film will solve that problem. Total investment was about $10.00, and there's no issue with being able to escape from the inside if needed. ...............Arctic Traveller