Dave,
I understand your intent to get the customs section cleaned up and it has a lot to do with 1) accountability and 2) transparency. I make a lot of customs myself and also purchase a lot of custom items and I think if we can separate some of the sections out, I think that will help a lot.
Just my personal preference, I would usually follow these steps:
1) Interest Thread: create an interest thread for what I plan/want to do. Any updates would be shown here, but no pricing, no sales, just a sort of WIP and to gauge interest.
2) Item/Figure Sales Thread: same interest thread, but I update the first page with the pricing info, shipping estimate, who's paid, who's not, tracking, etc. and change the thread title to reflect that deposits are being taken or ready for shipping, etc.
3) Artist Showcase Thread: once final pictures are done and shipped, I would add it to my own thread like Seb (Elvis) does and then link the original Interest/Sales thread to it.
I think having the first page of the Custom Thread be the starting point would be helpful because it shows who you are, what you've done, etc. We'd then update the thread with any completed works as before, but keep the sales/interest thread private and only visible to members who have accounts and not guests. Guests can still view the customs thread with no problem, but they can't access the sales/interest thread.