[RoadKill69]

Apparently everybody's system is different. Here's what worked for me, and based on the similarity of the external path to the internal path, I'd say anyone having trouble with the other suggestions here might want to try it:
Move the folder
/mnt/sdcard/Android/data/org.xbmc.kodi
to
/storage/<my external sd card>/Android/data/
and edit /mnt/sdcard/xbmc_env.properties to read
xbmc.data=/storage/<my external sd card>/Android/data/org.xbmc.kodi/files

I had to do this because I took T-Mobile's offer of a free phone (Samsung ON5) and only later realized it only has 8GB on board and blocks adopted storage without root. People seem to be having trouble rooting this phone, so I'm leaving it alone for now.

This brings up another question, though. When I run Kodi with these settings, everything works fine and my data is staying on the external SD card, but I am still losing 50 MB of internal storage on the first run. I can't find the additional data, but I do see a 25 MB file called /storage/emulated/0/Android/obb/org.xbmc.kodi/main.161001.org.xbmc.kodi.obb. Is it also possible to move this file to the external SD card, and if so how?

Thanks for tip this work for me on my Laser B-18 Android set top box

[AbRASiON]

Has anyone done what's in this thread, on the ChromeCast wGTV? (the new one)
https://forum.kodi.tv/showthread.php?tid=364246

My storage doesn't seem to be showing up in the same paths as others.

[AbRASiON]

Anyone? I've now done the text file trick, it has still not worked.