I don't think a van will do it for me. I sometimes need to climb curbs and ride off pavement for work.
There are Ford van 4x4s at approx +$4k and GM have(or had) factory 4x4 options.
The high center of gravity of a van might be a problem if the terrain you're driving off-road on is pitched steeply enough, but the ground clearance, wheel diameter and chassis design of the E350 are all pure truck, and one-ton truck at that. Of course, if you're talking about four wheel drive then that's a different matter.