Fellow Packer fan here! I totally understand your dilemma. I don't know how you got on the invite being a Packer Backer?? But, I think I would have to tell Bud, I am a devoted Packer fan and have to cheer for my team. You could sit quietly, be diplomatic and not cheer. But is it worth it to you? It would not be fun for me, if I couldn't have fun cheering for my beloved Packers.
Also, by then, you will know if the Packers suck. Then you won't have to worry about not cheering.