I have dealt with the 60/40 door rattle a few times. Taking the advice you got from folks above should solve your problem. You just have to fool around until you find the fix that works for you.
I have wonderful news though! You're driving a camper van around. It's a house including it's contents rolling around on a vehicle chassis. What's more, you take it off road probably! Just about the time you solve one rattle another will present itself.
My kids don't miss traveling in our former SMB at all because I always kept them busy chasing down rattles while we were on the road. Makes for a fun game for a minute or two, then there's the rest of the time you own the vehicle.
Have fun!