Hi Keith. Thanks for your compliments.
Often when I write about Paul, I get critical responses, which say this can't be right for various reasons. Yours is one of the first to be singing from the same hymn-sheet.
I'm broadly familiar with what you say here, but you've added some details I didn't know.
The connection between John the Baptist is an interesting one. Religion and Politics at the Dinner Table wrote an article about this a while ago: https://medium.com/bouncin-and-behavin-blogs/was-john-the-baptist-the-true-savior-67d9a80c66f6. It's also interesting that you make a connection between the Mandaeans and the Essenes/Therapeutae; I usually associate Jesus with the latter.
It's good that you are familiar with Mead; he is an important source. From the point of view of Gnosticism, I assume you are familiar with his Fragments of a Faith Forgotten.