Ill certainly give it a go although i have tried this before. It makes sense to bring out the upper mids i guess.
Setting tone knobs is very dependent on the cab you are dealing with. While I too find a slight cut in bass and a moderate bump at 600hz works great with my PBass and my AE410, that surely won't help you out (IMO) with the voicing of the 1212L.
The closest I got to my 900 sounding decent with the 1212L was a slight bass boost, a large bump in the upper mid setting and a pretty significant cut in the treble response. This at least helped widen the attenuated deep low end of the 1212L, giving a better ratio of lows to upper bass, and also plugging the pretty significant hole that cab has in the upper mids, while keeping the top end from being too shrill.
Still not the greatest match-up IMO and IME, but 'OK'.
Regarding the Gramma Pad, that can be moderately helpful on hollow stages, but since it only impacts mechanical coupling (not acoustic coupling), it will have virtually no impact on a more solid stage or floor.