After purchasing and modifying a wedge tool, I was able to gain the clearance I needed to pull the rivets on ribs 1-4 where there was interference with the wing walk gussets. I then continued down the spar riveting the center 2 rivets for each rib. After 2.5 hours of work, there are no more clecos holding the ribs in place, they are all riveted to the main and rear spar.