Some folks in your situation have been successful in satisfying home owners indentures of restriction, or local truck parking codes. They buy magnetic sign material, paint a matching color of the van and put over carrier logos when parked in no commercial areas
Another thing you might consider is alluded to above. Buy a cheap roof vent; the hinged lid type. Remove the Qualcomm antenna and antenna mount and set them aside. Cut a hole in the roof as described in the vent installation instructions. If there is a fan and motor with the vent, remove them and save in your house. Using the holes needed to fasten the vent, turn the antenna mount upsidedown and mount on the under side of the roof and fasten the vent framing atop the roof at the same time. Now mount the Qualcomm antenna onto the antenna mount so that the antenna clamp is about even with the plane of the roof. You may need to modify or shim the mount to allow this to fit properly and allow the lid to full close. Lower the lid and seal with silicone caulk if desired to get a tight seal. When you're ready to sell the van, reinstall the motor and fan and charge the buyer a few extra dollars for the nice vent.
You might even be able to garage the van with your new lowboy Qualcomm.
Terry