Quite a few states allow for delivering your ballot completed ballot via fax. Check the fvap website or your state's election website to see if this is an option.
In Taiwan, many 7/11s and Family Marts offer faxing services along with the copy machine situated by the ibon machines usually. You can also use online services such as hellofax.com, www.efax.com, among others.
At this point, it's best to try to fax or submit your ballot electronically from Taiwan given the possibilities of delays in mailing back in the US. But there's still time in most states to register and use a provisional ballot and to submit your ballot via fax, electronically via email or online portal in some states.
Thank you for voting this election and taking part in our democracy!