I would if
- the van was all the way "up to snuff"
- with a correctly installed class 3 or 4 hitch
- with electric brakes on the trailer
- with a WD hitch

For mileage, you may do 8-10 if you keep speed under 60-65. If you are crossing high passes > 5000' with a simple carb, mileage and performance will suffer.