Did you check both Ford fuse panels, there is a separate fuse box for trailer lights and there is a good possibility it is wired into that one, (I think it is under the hood, not under the dash).
if it is the same as our 06 Winnie Outlook, there is a separate wire in the harness for this light. Ours is an LED bar, so not likely burnt out.
As Paul said, the Winnebago website is not working properly for the diagrams, but check back tomorrow or phone Winnebago service.
Ken
2006 Winnebago Outlook 29B E-450.
2012 Honda CR-V AWD
Blue Ox Aventa LX tow bar and Brake Buddy Vantage.