Standard 1/8" aluminum pop rivits sheer way less than even machne screw limit (memory says 250 - 400 lbs) But they'd also be subject to fatigue too. I'm thinking nylon bolts, but didn't see any at Home Depot to try. When I was a tween we used a single grade 8 1/4-20 as a sheer for our New Holland hay bailer. Once my dad tried a grade 5 (all he could find) but it was too ductile and sheered on start up. Lesson learned, strong but brittle failure was needed.