At first I had thought about something like this:
First Breeding
1. Spinner Blast X Piebald
2. Pastel Het Piebald X Pastel Het GS
3. Fire OD Het GS X Butter OD Het GS
4. Spinner Blast X Firefly
5. Fire OD Het GS X Firefly
6. Spinner Blast X Fire Pin
I was thinking about getting 100% het piebald as a result of #1 above and then breeding the het piebalds to see if I could end up with some amazing piebald.
Same idea with #2 concerning GS, but of course this would be a long term project.
The possibilities are endless as you know...and I like your pairings as well that with a little luck will give me piebalds and possibly super pastel pies as well as GS right off the bat. My idea, it seems would take quite a bit of luck on the pie combo idea. To speed things along, I think I would need a GS and/or Pie (not het) but not sure I really want to go there. Have plenty invested in this little obsession of mine already!