Was playing around, and found out another method of making it easier to defeat all the people in the encampment
If you go down to the Stables and kill one of the Horses there, it will also initiate the "Slaughter the caravan" objective, but only like 2-3 people (including Calisca) will show up to fight you. After you are done with them, you can go up back to the Campsite and deal with the rest
Hope this helps!