After returning to the homestead, an old friend is going to pay a visit and tell you that Johnson has gathered the leaders of the tribes to talk to them. You need to get to that meeting and assassinate Johnson to preserve that land. While the water is supposed to be well guarded, the best way in is actually from the water. Get into the water but swim out to sea and approach from the east.
When you hit land, watch out for the bears nearby and start climbing up the trees and cliffs to get closer to Johnson. Soon, you'll come to a large cliff. Climb the cliff and you'll see a house at the top with a couple of guards nearby. Walk behind the house and start climbing the next cliff. You'll enter the restricted area from the south and should find a tree that has toppled.
Climb up the tree and make your way across the trees, over road and to the top of the cliff closest to Johnson's house. Don't pull yourself to the top of the cliff just yet because there are patrols that will be walking along the road here that might see you if you pull yourself up. Wait for the patrol to cross back to the right (east) and then head to the left of the nearby building. You'll see a tree with a platform towards the top. Approach that and you'll see a cutscene. After the cutscene, climb to the top of the tree.
From this tree, jump over to the main house of the complex. Walk to the front of the building and look down at Johnson. Assassinate him from here. This will complete two of the three constraints.
After you've killed Johnson, you need to escape the complex. Start running for the water. On this level of the cliff, look for the section with birds around it. From here, jump towards the water and you should land in the water. This will complete the last constraint. If you don't find the spot you're looking for right away, just try again. It took a couple of tries to find the right spot because there's quite a few. Just don't travel too far south because there is a point where if you might leap into a pile of leaves but the memory will end mid jump because you've gotten so far away from the restricted area.
