The four bolts you refer to are actually Allen bolts and Harley is over-torquing these during assembly. We managed to remove three of the four in disassemblying our 750 but had to drill the last one as the Allen hole stripped out when we attempted to use an impact torque driver (the last resort for over-torqued fasteners). I can understand your frustration in trying to remove these. When I had to order a replacement bolt they tried to explain it away as being the torque lock used which is pure BS. The **** bolts are over-torqued. period.I was finally able to complete some additional mods but unfortunately, had to pay the local Harley shop to get the 4 hex bolts loose so I could install the luggage rack. I tried everything to get them out but after breaking an extractor tool, I knew it was a lost cause. I was spending too much time on it and paying for too many tools that failed to help.
Nice review of your modifications so far and thanks for the photos.