You could hide in a bush near the horde cave or their two other feeding and drinking locations, and use attractor/pipe bomb or grenade combo or attractor bombs and proximity bombs placed beside explosives. The MWS is a pretty unstable weapon with low ammo. Unless the environment has explosive trucks, barrels, and suitcases (like the death train horde), it's not a great horde fighting weapon. The US556 is far superior, but takes a level 3 at Tucker's camp.

The hordes at Lost Lake are far bigger than the ones in Tucker or Copeland's area. If the shit hits the fan fighting a horde, park your bike a ways down the road so you can escape easily. If you park it too close, you will be swarmed trying to get on your bike. Stamina cocktails are excellent along with focus cocktails for horde fighting.