Unlike F350/450/SuperDuty chassis, Ford does not provide a 12V charge line on the F53 platform. That is left up to the "body builder" (i.e., coach manufacturer).
You can dig some information out of the Body Builders Layout Books
, but no diagrams for the F53 are there (usually). For them you need the Ford maintenance manual for your year chassis. I have a DVD for mine.
Winnebago has put many of it wiring diagrams on line
I'd call Winnebago and ask them where the charge line is.
You could also send a private message to Grant Harris (iRV2 user "grtharris"). He's very knowledgeable about Ford and Winnebago Fords in particular. Here's one of his posts
that may help you.