The difficult part is finding an allen bolt that is slightly longer so you can make use of the extra threads that the stock bolts are too short to reach.
You could just skip using the middle bolt on each side? On my '13 I just have the middle bolts finger tight with some lock-tite on them to keep them from falling out. It's way to hard to get the torque right with three pinch bolts...
I had problems finding these as well. I ended up finding a place that had some that were close but the OD of the head was to large. I had a buddy that is a machinist turn the head down. I think he did some extras for me I can look and see if I have any left. I am in Chicago for the week at trade show so when I get back I'll take a look