I found a thread from 2020 in Gatherings & Meetings labelled Texas Riders for RAGBRI 2020??, but I see that you were already part of that discussion. I recommend that you re-read it and try some of the suggestions.
If I were in your spot, I would start by learning all that I could from the Ragbrai website. That might lead me to a charter that fits. If not, I would just look at past threads. Your questions have been asked before.