Does this have a engine mount that is easy to unbolt that stops the front to back movement?
If so, unbolt one end and swing it out of the way. Leave it in park. From behind the vehicle come up to it with another vehicle. Put a used tire with no rim in between the two or some thing else that will not damage the vehicles. Then push into the rear bumper of the Van. Since it is in park the engine will roll forwards and give you MUCH more room to work with.
Block all the wheels to keep you body safe one the rear vehicle has pushed up again the van.