im not ml/56 sub for sleepga 2, but it lands
with my set/merits (enf duration), sleep lasted 2:38.
They also don't appear to have any real resistance to Bind at all. I was able to 1/1 a Manifestation+Bind on all 6 of them right after Saboteur wore off (no food either), while they were still sleeping.
Not that this ambuscade is hard or anything, but you could also do kite strat while DD or RNG wail on it from behind while the rest of the pack is bound in the middle.