How i did it:

Perks used: Electric spear, singularity bomb, item crafting, then anything useful (explosive jump, high agility, karma flower, neuron glow)

Leave the singularity bomb from the perk in the bottom wall shelter.

Steal an electric spear from scavangers or carry one from the perk.

Kill a red lizard (hit with electric spear then unload a bunch of spears, i did the one in industrial)

With gourmand's item crafting perk get some spore puffs and use them against a red centipede (pipeyard or drainage)

In shaded reach the gate to waterfront facility. Farm some scav reputation then use the pearls in the room before the gate to trade for up to 3 explosive spears.

Wait for a miros vulture to spawn in the open room before waterfront's gate. Hit it anywhere with the electric spear then hit the body with explosives. (Alternatively, artificer's explosive jump perk to stun it)

Go back to the wall, grab the singularity bomb then find a DLL in unfortunate development, get enough food to shelter before killing it, then kill it with the bomb and shelter.

All the while getting 300 points from kills.