The file that grows is located in /data/data/com.google.android.gms/databases/context[gmail account address].db
Since my phone is now rooted so I can GET to the file system, I went ahead and deleted all google play services data, left it sit for a few minutes to rebuild itself, and then I changed ALL the file permissions on that file to read only.
THANK YOU FOR THIS! Oh my god, I've struggled with trying so many different things in the past couple of weeks, but this was the one that worked for my LG Tribute (LS660). I guess I was a bit reluctant to root the phone, but after receiving absolutely abysmal support from Google, Virgin Mobile, and LG, I decided I had absolutely nothing to lose.
My experience was pretty rocky, though. I highly recommend NOT using KingRoot, as it installed a battery-charger screen that served up ads and was very difficult to remove. I ultimately used
method 2 from these instructions to remove all traces of KingRoot and replace it with SuperSU. I believe you can use a SuperSU apk to root the phone more safely from the start.
For anyone not technical enough to understand Desinia's instructions, after rooting the phone. I installed Terminal Emulator by Jack Palevich. I used UNIX "cd" commands to navigate to the above directory, and then used UNIX "chmod" commands to remove the write permissions from the db files. I recommend just Googling those commands to find out how to use them. Note, if you need to change into a directory name that is very long, you can use the "*" wildcard to match any string, but it needs to be a unique match. The chmod command is also a bit weird. You'll end up doing something like:
chmod 440 <filename>.db
Google Maps was a bit wonky at first, but settled down after a reboot. The only weirdness I see now is that, if I download an app from the Google Play Store, it seems to hang up right before it's completed. But all I need to do is close and reopen the Store for the app to install successfully.
And my phone is now back to being useful again. Thank you again, Desinia!