If the mod isn't working for you, here's a dirty workaround to disallow random mod-added props on newly generated rookies, at least:

Find the relevant .ini file in your customization mod(s), and change all instances of:

bVeteran=false
to
bVeteran=true

You can also find the vanilla game value VeteranSoldierRank=3 and change it to 1 (it's in ...GameData.ini -- not in the mods!) so you can access those items on any soldier above Rookie rank.

But there's a catch: You won't be able to use any "veteranized" armor props in the Character Pool screen, since soldiers in the pool are all essentially Rank 0 (even if you choose a class for them). Note, however, that this is specific to armor props; other stuff like helmets, face props etc. will still be available for use in the character pool, at least in my experience.

If you have soldiers with "veteran" armor props in the pool (saved during your playthrough, probably), they won't be affected unless you go inside the armor prop selection menus like "Torso", "Legs" and "Arms". If you do, they'll be reset to whatever's available in there.

Armor works... weird... in the character pool (at least in the base game; not sure about DLC). Don't go fiddling with your already customized / saved soldiers unless you've exported them to a pool file. This is good advice, with or without using the above tweak.



Some other notes:

- Alternative Mod Launcher can help you easily find the folders of specific mods, while Notepad++ (or similar) will allow you to make changes (like bVeteran=false to bVeteran=true) en masse.

- Be careful messing with the game files unless you know what you're doing, and even if you do, make backups beforehand.

- If you don't know the difference between files like DefaultGameData.ini (under steamapps) and XComGameData.ini (under My Games) then it's best to make your personal tweaks to both, until you learn the difference.

- Seriously, make backups. Just copy the files somewhere else before editing the originals.

- You can use the veteran trick on vanilla stuff too (in ...Content.ini), preventing rookies (including newly generated randoms) from using any props except the ones you allow, essentially creating a "rookie uniform". However, the above catch still applies: Any armor prop you "ban" for rookies will also be unavailable for customization in character pool.

- Did I say bac-- oh okay.