The only vantage point you can safely scout from is the house on top of a small rock cliff at the back of the outpost. There’s a watch post/tower on both entrances of the outpost, while several enemies will be hanging around in the main house. A recommended approach is taking out the snipers and lookouts from the highlighted posts below.
Next you can use the tall grass in front of the main house and take out a lone patrol there. From there, you can start picking off the enemies inside the house silently. This will leave the guys working on the yard and possibly at least one hanging around and around the pond house. From there, it’s up to you how to set your traps and ambushes to kill the remaining enemy forces.
At high tier, the same strategy applies though you may need to adjust depending where the enforcers are located. Always prioritize figuring out how to slowly whittle down the enemy numbers outward then move in. Like before, taking out the enforcers at range with silent weapons is still going to contribute a lot in increasing your chances of getting an undetected liberation.
Having a bow powerful enough to one-shot enforcers will make undetected liberation attempts for the highest tier outposts a lot manageable. Just get either the elite compound or recurve bow and upgrade them several times until their base damage is around 1800 or 1920. One-shot kills against these tough enemies are very important since they can easily call for reinforcements if they’re injured and can easily detect you even when crouching or in cover, blowing your cover before you can even make your move. Thes sample videos below will feature strategies surrounding this weapon.
You can refer to the sample videos below on how to achieve undetected or at least "No Alarms" liberation. Due to some random factors out of your control, like random animal attacks or friendly NPCs wandering near the outpost and triggering a response from enemies inside, you should adjust your strategy accordingly.