Secret Fort Entrances in Far Cry 4

I have been trying to take over all of the forts undetected in Far Cry 4 but I had trouble in the northern ones (Pagan's and Yuma's) but somewhat easier in the southern forts (De Pleur and Noore). This was largely due to the finding of somewhat secret or at least less direct entrances.
In Noore's fort you can climb up the mountain and grapple into the cave below. In De Pleur's fort you can find a hole near a broken dock that will lead you to a ladder that comes right into the fort. I looked (though not very hard) in the other two forts and found nothing.
Are there secret entrances like these in the northern forts?
Best Answer
From the Wiki:
http://www.ign.com/wikis/far-cry-4/Fortresses
Pagan's Fort: "Feel like avoiding the front courtyard entirely? From the main gate, turn left and take the dirt path to the northwest, which leads to a cave that brings you up, through the gulag’s cells, and lets out just a few feet from the alarms."
Yuma's Fort No major shortcuts listed in this one.
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Can you take Pagan mins fortress?
Pagan Min's fortress becomes weak to attack after you complete the last quest in the Balance of Power quest line. From this point on you can take Pagan Min's Fortress without allies or support.How do you weaken fortresses in Far Cry 4?
If the overseer is still alive, the fortress will be at full strength. But once the corresponding boss is deposed, the fortress will weaken as well. For instance, Varshakot has three alarms (and therefore three available waves of reinforcements) while De Pleur is in power.Where is the second alarm in de Pleur fortress?
De Pleur's Fortress Alarms Alarm Two: From the same spot, travel towards the main gate atop the wall to where the sniper sits. Take him out and the Alarm is in full view.Far Cry 4 - The Top Secret Place
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