The scent dripper that works durring daylight only sounds like a good idea. You sould get his attention that way. You also might want to try some rattleing in the hour that leads upto dark. If he's within ear shot he'll likely come in to investigate and hopefull give you a shot.

IMO this is what makes hunting whitetails so great. There's nothing like matching wits with a creature as witty as a mature whitetail.

Good luck!