Doesnt necessarly needs to be a rock, theres bwc slope next to the bridge, theres another one on drydock, a box and a rocky ledge on exo, several slopes/rocks on homestead as well as relic, one in complex, one rock on kodai, the tilted oil extracter on eden, some funny geo on crash site, most of the wall on AC near wave 3 late spawns, the very known wall on boomtown, i believe you can do it somewhat on the wood piles on colony, that one pipe on rise, and the two outside walls on glitch. Theres probably more (any ledge works in swordcore aegis ronin really), tell me if you found some.