I dare say, an extra Climber would also work, as I can then use one of the remaining Lemmings to mine under the blocker, which is facing Left, so they can reach the exit no problem, while the Miner is turned into a Climber only after turning around at the small wall near the trapdoor. Saving 100% would make for a nice talisman in a level pack, while the extra Climber will make it more forgiving at the beginning if you're unable to isolate the 2nd Basher.
EDIT: Actually, never mind. Releasing the blocker is not that straightforward because of breaking the bridge and lemmings possibly walking back.