Have you thought of TAD to Base Maint. if you're not all ready? I picked a lot that way.
But as far as a License goes, and studying for one, there are a few Authors of books for the Journeyman, and Master Licenses of most all states available. So you could study while deployed, and come back ready for a test.
This is just one... (Of many out there.)
http://www.mikeholt.com/examprep.php?id=examprepgeneral
