They would guard the base camp, tend the horses, etc.
That's a great idea.
You could also expand the concept to make it feel rewarding to have such hirelings.
-Pay to have someone guard for example the player stronghold
-Once in a while you return to the place, and you actually see a bandit or a wolf battle with the hirelings
-You can actually engage in the battle with them
-Or sometimes it could just be the dead corpse of an enemy which the hireling already defeated, so you can loot it without much trouble
-And sometimes no enemies appear at all, to keep it realistic
Effectively you get some bandit gear or wolf pelt as reward for hiring them, if you're lucky.
So there is a feeling of reward for spending that money.
It gives the hirelings a purpose.
It makes the setting feel alive.