Here is a link to a photo of a saddle pack ...
http://www.kingslynnmodelshop.co.uk/...FeXMtAod5A8AUQ
My friend had the Exotek cf set up and was able to use a regular 5000 mah hard pack with it. He did however have to make a few mods but of the top of my head I can't recall what they were. I will try and get a photo of his set up and ask him what he did.
I would also search through this thread again as I am sure I have seen a few photos of peoples s2f with full cf and no saddle pack, but again I can't recall who's.