The vent tube runs from the top of the filler neck tube where it meets the quarter panel and dumps off into the inner framerail next to the filler neck tube. I seriously don't think it plays into the filling process since it doesn't even touch the tank and the pump nozzle is more than surely pass the exit point of the filler neck tube (nipple connection for vent tube at top). It's main function would be venting when the gas cap is closed.
I have always had this issue with all my 2nd generation Chargers and I've owned them for over 30 years now. I never leave the pump on auto. Sometimes it is the position of the nozzle outlet in the filler tube. I always hold mine such that the tip of the nozzle is against the outboard side the filler tube, not just sitting in there. It is a pain in the butt, but sure beats having to clean all the fuel spillage off the quarter.