Well the tire issue may have something to do with the short wheel base of the veh's I'm associated with.
If you have BOTH wheels on the ground with a true-trac you will have posi traction while the torque is applied. The moment you LIFT a wheel all bets are off. In your van, I highly doubt you'll do that LOL...
I guess if I was you... I'd get the true-trac. If you lived in Florida I'd maybe spring for the locker.
Also - in case you've never heard of "crab walking" try googling it. When you're towing in the snow/slick road you're more likely to loose traction with both wheels spinning and slide sideways.