We had no problems driving 4 vans (each with one or two tandems fitted horizontally, on the back) across the country and back during Race Across America. We also had the same arrangement on a van during the Hoodoo 500, plus the drives to/from SF, CA <-> So. Utah
Note the front wheel locker is down in the pic, adding to the width. The bikes are about the same width as the van's mirrors at the widest points, with the bikes secured.
