Large, heavy, high profile tow vehicle with the power of a base model midsize suv = major struggle in the mountains. At least the van will allow for a more streamlined towing of the trailer than a pickup, aerodynamically.
Will it tow safely? Yes, but you'll likely be in the right lane with your 4 ways on up every pass.
However, it's not much different than towing it with say, a 20-25 year old small block pickup which has been don a million times.
What you give up in a little bit of torque, you probably make up in gears.