[KamperBob]

Andy, IMHO a gap filler is your low fruit. A wide open bed fills with separation bubble effect. Actually two bubbles. Mirror image vertical plane down center. Sides and top wash back. Up wash behind cab. Yes down wash under nose back to tailgate. Little eddies behind add a bit more flow up over the tailgate. Flows forward also on the bed bottom. It's all about flow balance and boundary condition continuity.

Note your loft nose is angled and the top edge is radiused. I wouldn't bother with a high deflector for profile effect. In plan view you have sharp sides so bow splash around both sides. You could add on to the nose instead. Make it hollow for storage with sides that open. Over the ball is a great place for extra weight stability wise. That's where I put my generator. Does both actually. Otherwise gap over pin is value lost.

Quick reply. Rough I know. Food for thought?