Heh really. Get a young corn.

But seriously, I would try to either find a store that would trade or a snake owner nearby with some young corn snakes. Pinks just don't really do it for BPs...even multiple ones. Best bet here would be to move him up in prey size, but slowly. Don't just thrust a hopper in front of him as it might 'scare' him being so much larger than he's used to seeing.