Well you could use a HP sabot from MMP and cut the petals off leaving just the .45 caliber base. It's pretty much what a sub base is anyway.

I phoned a few places around here but they only carry the standard revolver wads in .45cal. In .50cal the felt wads are available, I've heard about leather and thick cardboard wads, those two I can produce at home. Will try them next time I go to the range and experiment a bit. Do I need to lube the bullets themselves like a sidelock's conicals? I only thought of the lube after I've resized them, maybe something like Lyman Gold before re-sizing?