Ann,
I am an addict in recovery in NA with over 9 years clean. Now, I have never been in a situation such as your husband's. I know a few people in my fellowship who are. They don't really discuss their situation much, mainly for the same reasons your husband doesn't want to. They don't want the debate or drama that inevitably happens with disclosure. The people who I have heard share about pain meds in recovery have said, their doctors are informed that they are an addict in recovery and what that actually means. They inform their sponsor of what is happening, and their close recovery buddies and family members, etc. And last but definitely not least is they pray and meditate about it for guidance. That way everybody is aware and informed of whats going on. Some people ask their sponsor or recovery buddy to hold on to their pills and dole them out only as directed on the bottle. Others just have someone check frequently and do a pill count to help ensure the recovering addict to stay on track. Also the idea is to take the minimum amount needed for the shortest time possible. There is a pamphlet that NA has, its called In Times of Illness. It talks about this very thing. If you can't find one in your area, then check with your region or NA World Services online.
Good Luck