You still can't beat a switching regulator though...
Or switch to using a switching regulator (pun intended) and get 85%-95% efficiency.
Why do you need two supplies not just one?
I'm pretty sure that can't work without shorting the AC input directly across two diodes. A full diagram would be needed to check.
How about just converting it to a half wave? Can't you just pull out some of the diodes or replace them?