funny you should pick the working stiffs as thats the one i chose to use for a base when i see it as well.
as katarynna stated you do have to clear ALL zombies from the poi before it is rendered safe enough from spawns in the covered radius.
i know i have a disadvantage over most players on one regard and that is, i know where all the spawns can be. next is not telling anyone how to play... just showing my normal way i do this poi and i enjoy it it that way and thats why i play the game... because i enjoy it.
0. dont worry about looting until done as the loot is not going anywhere.
1. kill the zed in one of the sheds on right side of parking lot.
2. climb up on the stone fence from trash dumpster (kill the ones you see in the back area in that spot only).
3. use 2-3 ladders or frames to get up on next roof (dont fall down or go on the small roof).
4. head left staying on top of orange roof til you get near the 3 in left front corner of roof (one may be a bird) (dont hop on the wall but lay down 2 blocks horizontal and crouch on them).
5. use bow while crouching to get a nice steady hit shot kill bonus (should be a one shot even without a perk).
6. break out your club or whatever you use because once you step on the main roof you will wake up the last dude/dudess that is hiding up behind the ac units on the highest roof section sometimes it can be a bird. (when high roof is clear place down your bedroll as it could be useful if you die below).
7. now traverse off of the orange roof to head thru the front door.
8. go thru front door and kill those that waken and attack (make sure you walk in the baths to be sure one did not get stuck.
9. go thru the floral/wire caged area clearing them out.
10. go thru the kitchenette/lunch room.
11. go out to the loading dock. (kill the 2-3 remaining zeds including the one in the trailer (he most likely comes out anyways for the party).
12. now go left up the ramp where you see a car and maybe one more zed.
13. go into the little office making sure its clear.
14. now go up the ladder (all should be safe now).
15. craft a hatch and place it on top of the ladder.
16. go to the highest roof and place down your claim block.
17. welcome to your new base.
18. oh, you can now go down the hole in the roof to loot the treasure room and open the door with the switch/keys. then you can loot the rest of the establishment.
i have never had any respawn in this poi and yes it is my normal way/path i do in it. but please feel free to do it as you wish.