there is no stock sprinter that hasn't got sagged suspension so even that's not a real good starting point.
Look blair I see where your coming from and theres a place for the theoretical and a place for just trying it out. The best pinion angle of the diff is pretty fairly universally accepted, and I can't see how you would find this out by trial and error.
Also why don't you calm down and show constructive answers instead of insults. We are all here for the same reason and no-one provoked you initially.