How to save an ArcMap 10.5 MXD as a 10.4 MXD

[JoshJones9]

I am using ArcGIS 10.5, and I need to frequently save MXDs as 10.4. It would be nice to be able to use this tool (How To: Save map documents in ArcGIS 10.x to previous version of ArcGIS in batch ) be able to batch process. I set up the script, but it does not work to save as 10.4. I can save as 10.3 and earlier, but it would be so much easier and cleaner if I was able to figure out whey this doesn't work for 10.4. It tells me that my MXD is originating as 10.4, but I even saved a brand new clean document in 10.5 and I get the same error:

Has anybody figured out how to use this tool to save 10.5 MXDs as 10.4 MXDs?

Thanks.

[MattWilkie3]

Here's an AutoHotKey script to make saving old versions with ArcMap slightly less painful:

Key sequence for ArcMap 10.6 to save copy of current map as 10.3 · GitHub 

[MattWilkie3]

Updated to save as 10.4 instead, which was my actual goal to begin with. The earlier version of this saved as 10.3, which wasn't necessary because 10.3 is available from ArcPy. (Doh!) It's only versions 10.4 and 10.5 which are unavailable.