I would step mash(multi temp), fine crush, mash in only 5 gal, sparge the other 4 and add beano and amylase. One at a time or all. You should have 80-90 efficiency with biab. Your mad temp pro my higher than your thermometer tells you. Slow into the single infusion temp. The temp keeps rising longer than you realize.
Sent from my iPhone using Home Brew