I think you have a great plan. From my recent research and reading Tom Shroder's Acid Test: LSD, Ecstasy, and The Power to Heal, and Myron J. Stolaroff's The Secret Chief Revealed, one thing Leo Ziff did (he provided over 3000 MDMA sessions) was have his patients bring a chronology of meaningful photos from his childhood, to a therapy session 2 weeks before the event. The therapist weeded through the photos and reduced the number to relevant ones and put them aside. Right after the event as the patient was coming down he was asked to look through the photos and talk about anything that came up.

After all, isn't your purpose to get at the source of the feelings of rejection, loneliness, and social anxiety?

I don't think you mentioned dosage. It seems to be a very important factor from what I have read.

Your plan reads like a very thoughtful one and I wish you the very best. I suffer from childhood trauma, and I too have difficulty getting at source within the context of talk therapy. Even EMDR has not gotten to many of my core issues, although it has been more helpful than many things I have tried.

It may be useful to read the two books I have mentioned. If it was me doing it, I would look for a fellow Childhood Trauma sufferer who 1) had worked on his case enough to have reached a good level of education on the subject, and 2) , is a kind and compassionate person, and 3) is reliable and will show up on time and is willing to free himself from worldly duties for the duration (about 2 days in total)., and 4) understands what it means to be a non-judgemental, non-projecting,..... witness. The reason being, I would want to make sure that my person really knew first hand what is at stake, but that's just me. I have enormous trust issues.