Hey Brandon,
I would definitely rule out Dez in this situation. He has been a shaky wide out all season long and unpredictable from week to week. If I were you I would go with Fitzy. San Fran's D is great, but Larry has a knack for big games in the prime time slot. With a mediocre running attack the SF will stuff, look for Skelton to be slinging the ball to Fitz and the WR core all day.