Thanks to everyone for all the posts. Here's what we decided.
After some phone calls Tuesday, it looked like we could get the ID to take with us if we showed that there was an urgent need. The rule here in MD is that they mail the photo ID if you are over 18 and under 65. I wanted DS to take the Learner's Permit test (kind of force the issue, you know???) However, we decided that there's enough pressure right now to just get everything ready to go. The express office of the MVA issues ID's, but not learner's permits, so we decided to go the the express office and just get the ID. I showed a copy of the airline confirmation and the expired ID. The worker acted all serious, but it wasn't a problem. We paid our $15, got the ID, and now I can focus on getting laundry done and packing! My last day of school was yesterday, and I managed to get my classroom packed up Tuesday and a little more yesterday, so I am ready! Thanks again everyone!!