I used revolver against them. Don't remember what difficulty setting I played, but there was enough shells, at least for self defense. Finding some place where they cannot attack you from multiple directions and having fully loaded revolver was usually enough to fight pack off.
Also, like regular wolves, they get terribly scared if you hide in a car
Edit:
In the last update they fixed "unexpected items spawning in Interloper games".
So, when I found hunting knife in one of my latest Interloper playthroughs, that was most likely a bug.
In my game (Hard difficulty) I tried hiding in cars from Timberwolves and they don't run away or give up. They just stand right outside the car door endlessly growling. If I pass time, they don't budge and just keep growling with a full morale bar. If I go to sleep for an hour, same thing, they just wait outside growling. If I go to sleep for 2 hours, the morale bar disappears and they seem to go away, but as soon as I exit the car and take a few steps away from the car, the morale bar reappears and the timberwolves come right back after me. Standing and fighting them was the only way to make them retreat.
I have sad news for you

Episode 5 is not yet released. And IIRC if you completed steam tunnels, you are pretty close to finishing Episode 4 as well.
I finally finished Episode 4

... but also... I finished Episode 4

. It was really fun and I'm sad that its over.
Also... confirmed that Episode 5 is not available yet
Also... I was nowhere near done when I finished the steam tunnels

In retrospect, I was only about halfway done at that point. To be fair, I had a bunch of side missions left to do, but even the mission to the mine by itself ended up taking a long time because I kept dying. The journey to and from the mine is tough because of all the wolves, but it also seems like there must be three different bears on that map, because I encountered a bear both at the lake hut, as well as blocking the entrance to the mine facility. So many bears

The final challenge is pretty tough to complete without getting killed. I died dozens of times trying to complete it. I also encountered a nasty glitch that made the ending impossible to complete, so I had to reload from a prior save:
The final few parts of the episode are very exciting though. Very enjoyable