depending on how you wanted to do it, the bag would want to almost go out in the middle. It would also depend on the types of bags. don't know if what i'm saying to you makes sense but hopefully it does.
sorry, I was thinking you wanted to do both uppers and lowers on a pivot, I think that just one pivot would be less likely to do what I was talking about
i have seen some pics of this done before. fixed top and the lower pivots on the lower bar and has a dog bone set in to hold it in place throughout the range of motion, with no balooning