Yes, that was my next step: just fabricate one. I was hoping I could just buy one out there. However, “afisstore.top” is a scam, I believe. I have already been scammed by Nokonshop.xyz for that same trunnion, and afisstore.top uses some of the exact same wording in the “about us” section. Both very believable websites though!
So at this suggestion of a marine electronics outlet, who had a trunnion for a wider model for sale, I bought that wider bracket and just cut it down to the narrower size I needed. Worked great! Thanks for all the help out there!