Solved my own problem this time - noticed there are long Bronco bolts and shorter generic ones for the roof rack. Looks like Bronco bolts go on the front crossbar (visible to the world) and on the plastic cover while 4 generic shorter bolts mount rear crossbar to mounting bracket. Longer bolts bottom out before securing cross-bar completely.
Oh... and each type has a different Torx head size - Bronco bolts fit the TP in the supplied kit - not the generic ones.