Update: ended up tapping it myself. Easier than I would have expected. Just got a cheap metric tap and die from Harbor Freight and had the mirror on quick.
This is my second time trying to order a replacement mirror for my driver's side after it was absolutely destroyed. The first mirror was through OEM ford parts online and I had to return it due to the OEM screws not going in all the way. The second time I decided to order it through ford.com...