(and an RP side note on NCR) The town that is the Strongest in the western wastes, with it's own Army, and at this time still allied with BoS, wouldn't stand for a group in town like that, the army would walk into town, with PA paladins and smoke the place.
This reminds me GTA.
We could have some step to step reinforcement... One wave every 5 minutes, after 10 regular forces are dead.
I mean we could have 5 waves of reiforcement.
1 Backup weaker than the regular forces some melee not used to fight (15)
2 Regular Forces, with leather, metal armor and 1&2 class weapons (20)
3 Strong forces, with combat armor and 3 class weapons (15)
4 Elite Forces, with Power armor, 3 class and rare weapons (like gauss, Gatling, HKGE11) (10)
5 An army gathering all other waves (15+20+15+10=60)
Then
1 again, 2 again, etc...
Guards unlootable and no rewards...