Take a seat

[LDB]

Vans especially are challenging for enough space to carry personal items. Here's a chair option that folds much smaller than most.

REI Flex Lite Chair at REI.com

 

[Slo-Ride]

Heres one that may even roll up smaller..Of course you may need to bring a tree with you. Never used one but hear they are good

 

[LDB]

Looks like it might be comfortable but not sure about supporting it just anywhere. That's the good thing about the one I linked. It's usable anywhere. I think it's a little low to the ground as a compromise to small packed size but it might be better than nothing.