Ok I figured it out. If you install steam and the game with the default path (on windows, sorry other folks), this mod shows up in:

C:\Program Files (x86)\Steam\steamapps\workshop\content\262060\3160709390

Inside that directory, there are multiple folders. Three for each of the modifications, and then an "inventory" folder. The "inventory" folder defaults to the 3x, but you can simply overwrite the file in "inventory" with the one from whichever version of the mod you want.

Same procedure for the stacking mod. For me, it was located in:

C:\Program Files (x86)\Steam\steamapps\workshop\content\262060\3160705190

Just replace all the files in the "inventory" folder with the desired version.

Where are the additional files and how do we swap them out?

Why make it so "hard" to use this mod with your other mod? I can't make it work with the Stack Mod, where are the compatibility files?