Yep, it's confirmed. Destroying the masks counts as much as collecting them. This could've saved me a ton of time. Those hard to find ones would've just met molotovs, grenades, rpgs and the like just to give me a reason to spend money on ammo to empty my wallet.. Hope this helps others.
When you begin the mission, you should encounter about 2 wolves on your way to the den. At the den entrance I believe there is one or two wolves outside and one inside.
I suggest you kill all the wolves before hitting the red explosive barrels. Perhaps a bug occurs when you destroy the den before clearing it, thus there might still be one wolf alive within the then.
Aim for the head with your arrows. You should get two skins per clean kill.
If after another try it's still not working, you might want to check for your game's file integrity on Steam to make sure nothing's corrupted/broken.
Best Answer
I figured it out, You need to "look up" more when you jump, then it's easier.