It might be good to just dump the idea of counterpick stages altogether. They put too much emphasis on the first game. Like, if you lose the first game and your opponent has a sufficiently unfair counterpick stage after your ban, then the set is basically over. So you'd start the first game with stage striking (FD, BF, FoD, DL, YS, KJ64, PS), going 122112 or maybe 121221, then the winner bans a stage and the loser picks from the 7 "neutrals" (although now there are simply "legal" and "illegal" stages). You could have 9 legal stages (including RC and BS) but that might be too much.