When DH was active duty I think his were different than now as a reservist. During his last deployment as a reservist he had a POA that was good for 2 years from issue date (done during Mob process). It is actually still good another 6 months from now. It may vary according to deployment lengths. I have 3 copies I think. There are lots of clauses too in case he was MIA, etc. I actually never needed to use the POA though. But good to know that I had it if need be.
Your DH will surely have to get another when he deploys. They were one of the Mob stations I think, on his checklist. DH flew through the Mob (and demob, thankfully) stations as he went as an individual, not a unit. Yes, it is harder to get info as an individual, but there are more "pluses" going this way too.
How much longer until he leaves?