Ask for hair follicle proof that he has not used recently before anything other than supervised visits, and for random testing after to prove that he's not fallen off the wagon after his treatment. Ask that the court order that if he has again shaved (and this time maybe also shaved elsewhere) & they cannot find hair sufficient to test, that he gets no unsupervised time.
Joint legal custody is a pain in the neck if you have to run every major decision by him & you can't find him becaus eof his habit, so consider asking for some way to ask for approval of decisions and if he FAILS to respond, that means you are OK to go ahead & make changes... such as daycare changes, school or subject changes, doctor appointments & such...
Realize that "joint custody" for legal is often what they prefer, so they'll look for any way to make it work, though I'm surprised at someone doing that when he's an active and constant drug user... is there something he's accused YOU of that would suggest that you are not a whole lot more reliable than he is?
Well, never mind that... just realize they WANT to give both parents equal say in things... just odd if it's a drug-addicted say... SO... ask for some kind of accomodation so that if he refuses to agree to what's happening in the kids' life (school, docs, etc) AND if he fails to exercise visitation even when allowed, ask that it be terminated until he participates in reunification therapy and a series of supervised visits as well as teh repeated drug tests.