I had Proton 28 sessions. I too suffer from diverticulosis. I did prostox and would recommend it. They did not design prostox for 28 session proton but my rationale was that if it revealed sensitivity to radiation I would not proceed. I have no ed yet at 16 months at 70 years old. The diverticulosis during radiation caused a pocket to burst and I had some bleeding from that but not a big deal. In your shoes I would hit this hard, radiation plus ADT. While focal therapies can work I think grade 5 will be a problem. Don’t neglect the SBRT mri guided option either, that is showing low side effects. Be sure and have a spacer of some sort. This is all my opinion, listen docs from quality centers.