Under normal circumstances you need to get to level 31 to unlock the Many Must Fall perk in Zero's Bloodshed skill tree. This allows you to stay in deception mode for 10 seconds and is required to unlock the Unseen Predator achievement.

Here is an alternative method, if you want to get this achievement easier and faster:

Get a Bandit Technical vehicle on a Catch-A-Ride station. When you play solo you must reach the story mission A Dam Fine Rescue where you are tasked to get the five bandit car parts for Ellie in The Dust. After this sub-mission you will be able to spawn a Bandit Technical from any Catch-A-Ride station. You can also join a game of somebody who has already completed this mission to spawn a Bandit Technical vehicle.



After you spawned the car you must hop on the back - not on the driver seat and also not on the turret. Now comes the tricky part: Use Zero's action skill to go into Deception mode [default key: F] and immediately hop on the left or the right seat in the back of the vehicle [default key: E].



The camera will now zoom in from the 3rd person perspective into the 1st person perspective. At the instance the camera changes into the 1st person perspective switch seats [default key: C]. Continue to change seats for 10 seconds - even after your 5 seconds deception mode expired.



When you hop off the back of the vehicle [default key: E] the achievement should pop up. For all the afore mentioned steps the timing of hitting the keys is crucial and you will probably need to try it several times. It took me about 10 trials until I got the correct timing and the achievement popped up.

Disclaimer:
I saw this video on YouTube by a guy who did this on his Xbox. So all kudos go to him. However, I found no source confirming that it also works on PC. I can definitely confirm it also works on PC.