This not so much a guide as an exploit to make these easy to get and not lose characters to these like I have
When you get the call from lily do not go near the drop , make a note of the location, and start any other mission , clear an infestation, feral hunt etc and go to the CLEO location, now the beacon wont be sounding and you can loot freely. Well you may have a few zombies around but not the respawning masses or the ferals that can instantly tear a full health character in half.
Finish the mission and go back to the cleo drop get credit for completing it.
This might also be very useful to know for Breakdown and Lifeline later.