I don't get why the compulsion to push the limits and break the rules. Geez, just do what they say and avoid trouble. If you're doing an itinerary where weed is legal, get off the ship, partake, have some edibles, then toss the leftovers in the trash and reboard. Make sure nothing is left in your pockets/purse/backpack/whatever.
If weed is that essential to you, be it medical or recreational, then just don't cruise, in which case realize unlimited access to weed is more important to you than cruising.
NO, I am not anti-weed. I have no issue with medical or adult-use recreational. I just think rules are rules; we don't have to like them but we also don't have to try to get around them or share ways to break them and hope we don't get caught. IMHO the consequences aren't worth it.