Slicks to Leaf Spring Space?

Would 3" clearance be enough for a set of 10,5 X 29,5 on 15 X 6 wheels with 5" BS?
Maybe 1.5" clearance is enough, incase I decide to shorten rear axel some?
Picture is somewhat miss leading, since this wheel has 4,5" BS and I´m also going to use break drums without fins...
Your experience and advice would be of great help.
Thank you,
Stefan
20170730_140055 8a Slick clear.jpg