Wow, one of my favorite issues. Another reason rack bolts fail is when tourists ride off road and the jolting when you hit bumps can shear water bottle cage bolts right off. When the bolts shear off you are faced with what could be a difficult task (out in the field), of removing the broken piece in the eyelet. My solution is to mount the bolts from the drop out inside and attach nuts from outside the rack, so when they should shear off you just need to unthread them with the still intact allen head, and replace. You may need to use a button head type of bolt on the right side, so the chain avoids jamming in the small cog.