I stayed there for 3 nights in summer 2017. It's a nice hostel, great location. Has a small drying room where you're meant to hang any wet stuff so the rooms don't get damp.There aren't lockers though, and the rooms aren't locked. It was all walkers and cyclists staying there when I was there, so hopefully all reliable types who wouldn't nick anything?? As the only hostel in Tarbert itself, and right by the ferry terminal, it's where anyone looking for cheap accommodation would stay though, so I guess no guarantees.
Maybe if you just make sure you get all your hiking gear wet, muddy and smelly enough, no-one else will want to take it