Not sure about SBBW, here's sponsors with Fat/BBW sites:
Fat Pays - Young Fatties, Plumper World,Plump Mature, Video Fatties
SPACash V2.0 - Big Fat Beauties, Enormous Babes, 9Buck Fat Girls
Score Cash - XL Girls
Niched Sites - Fat Chicks Love Dicks
Adept Cash - Chubby And Sexy
Archive Cash - BBW Vault
Cash Maniacs - Chunky Angels, Nasty Fatty, Fatty Chasers, Fatty Gangbang
Flash Cash - Big and Slutty
Swank Dollars - Plumpers & BW