Have you tried the die that cuts threads in wood the same size as the lathe spindle? I was debating trying that so I didn't have to tie up multiple faceplates to keep more than one grit set up on discs, but I wasn't sure how well it would hold up. I've read comments on Amazon that said it would work, but I've seen some of the things people do on their videos that are very unsafe and wasn't sure how much credence to give that. Very nice design on your system. I was trying to figure out how to use the banjo as a work support without spending a lot of time constructing something and I think you just figured it out for me:)
I am glad I could help out. I have purchased a thread cutting die for my spindle on the lathe. It works amazingly well. I made up a number of pre-threaded pieces of maple. If making a bowl, I use wood glue + brown shopping bag paper + wood glue then my bowl blank. I have also used them for many other applications. I found a great die at "The Beall Tool Company of Newark, Ohio. Once you purchase this cutter, you can make multiple head stocks and even leave them glued to your work and removed from the lathe until a later date. I hope this helps.