Somehow I thought overseas voters had to have a "permanent" overseas address to vote from abroad.
You can vote from outside of the US whether you're abroad temporarily or permanently.
You can vote from abroad while traveling, working, studying, living abroad or serving in the military, temporarily or permanently. Use the address of wherever you are staying during the election.
You will be required to put the physical address of where you will be during the election on your Overseas Voter Registration and Ballot Request form, but it does not need to be a "permanent" overseas address. Many overseas voters are temporarily out of the U.S. for reasons of work, study or travel and they do not have permanent addresses abroad. It can be your school, or hotel, or office or home address - whatever is appropriate in your particular overseas situation.
Keep in mind that you can also request to receive your ballot online. Be prepared to download and print it to send back to your election office on paper.