Consider the weight capacity, too, not just the space. My Dodge Ram Van has a ten-foot-long cargo space in the back and I can fit 23 half kegs in there. It's also rated for up to 9,000# Gross Vehicle Weight (GVW). The van's weight empty is 4,800#. 23 full half kegs at about 170# each is 3,910#. The GVW then comes to 8,710# which means I can squeeze a few sixtels in the gaps or pile a couple of cases in there.
That said, a van should be fine for your needs, but make sure you get a van that has additional weight capacity.
Mike Hiller, Head Brewer
2277-A Dabney Road
Richmond, VA 23230