I thought about the tripod approach, but being in truckstops with trucks constantly manuevering around each other, Im affraid the tripod would get in the way. I figured a way to get it plumb due to the amount of lateral movement by loosening the "U" bolts that hold the mast in place, I use a small magnetic level the adjust the mast. Its not the ideal setup, but will work for now, until I have another brainstorm.
Set up your tripod on top of the rig