If you use 'Spherical' bearing/bush's or rod ends at the inner pivots of your wishbones you could align the inner pivot brackets/bolts on the chassis as per the 'Top' attached dwg so rearward shift of the top w/bone for more castor would have very little if any effect on the camber angle.
Jac Mac. ( Yeah, I know, Now he tells us- Sorry guys, its only because I have been trying to work out a solution for my own car in my head while working on other stuff - at least I am happy now
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