I haven't ever owned one of these vans, but I have a friend that delivers lost luggage (that gets found later) for Cleveland Hopkins airport.  That's all they've used for the past 15 years or better and I bet they're only on they're third or fourth van.  They put a ton of miles on and routinely overload with little maintenance.  I don't see how this situation could be any different and I'm amazed that the use that these vans have stood up to.  Maybe your experience has been different, but I wouldn't be afraid of them.

Mike