Has anybody had any success with downloading Steam Workshop mods (outside of Steam) and applying them to Production Line?

The good news is that I've found the mod folder (\Users\[username]\My Documents\My Games\productionline\mods) and follow online instructions to download Workshop mods. I've managed to grab a few that fill some gaps in component manufacturing.

However, the frustration is that after trying several different programs, I've yet to find one that will recognize and extract the .PAK version that Steam Workshop is using for these mods, and despite showing signs of Steam integration (greyed out tabs in the Mod UI), the game won't read the .PAK files directly.

All of the following extractors have failed:
Game Extractor Basic
pakexplorer
pakscape
QuickBMS
rust-u4pak
UnrealPakTool
VPKEdit

As an aside, I've also tried sites like AltWorkshop.com, which lists most of the mods I'm interested in, but every mirror they offer reports the files as missing, so I can't get them via that route.

Any suggestions?