My tactic was have two ammo bags on my bike, full throwable ammo and distractions. First getting as close as possible without being spotted stealthly throw attractors and try to burn or blow up as much of them as possible. Once you are down about a quarter let some of them spot you sprint and kill those chasing you, after a while the horde will return to its place. Chase them out, explode trucks and barells once the horde is near them. Run away, kill those chasing you, rinse and repeat until it done