I don't remember if I tried this (though I do remember I had some problems getting other solutions to work)
For not owning weapons in the game when you pick them up -
In the shop file try swapping the archetype numbers between the regular (campaign) versions of the guns and the Yeti versions. I think they have different archetype numbers meaning the game considers them different weapons.
Caveat - if this works you will most likely need to change the stats of all the Yeti weapons to include your new damages, FOV, etc. etc. so they behave like the campaign weapons.
Just theorycrafting (again)
And all this science, I don't understand... It's just my job, five days a week
I do remember that there were some problems, thats why the changed weapons never went to more than AK and Webley. Using Yeti archetypes is of cause an interesting idea. But to be honest, I think Yeti weapons are using the "new" damage values already, so I would have to look up where exactly the Yeti weapons are getting their data.....
I've… seen things you people wouldn't believe… Attack ships on fire off the shoulder of Orion. I watched c-beams glitter in the dark near the Tannhäuser Gate. All those… moments… will be lost in time, like tears… in… rain.
I do remember it being buggy when I tried to use the .menu versions of the weapons resulting in some odd ammo and other glitches. Wasn't sure if I tried the Yeti versions of the guns.
Hmmm just did a quick check of the two AK-47s in the shop file (Assault rifles/AK47 and DLC90_Assault rifles/DLC90_AK47) and although they have different disLibItemId numbers they both have the same archetype reference - meaning they both pull the same weapon data from 216180365620235801.ark
I wonder if they did it that way to reduce the amount of files and yet keep the two guns separate so that if you picked up an AK-47 in the campaign it wouldn't necessarily unlock in Yeti (and vice verse)