All the B-screw does is increase the tension in the spring on the top pivot, so if you disassemble that you might see another hole for the end of the spring (check inside the knuckle and on the cage). Easy enough to drill another in the cage, too.

Or if that doesn't do it, maybe you could find one of those claws you can screw a proper derailleur to (as opposed to the even crappier ones integral to the derailleur), and modify it to bolt onto the hanger and lower the derailleur an inch or so.