In the first room on the right there are 2 more boxes of rifle/SMG ammo and a salvage locker you can pry open with your axe. While you're there, light your torch at the burning barrel.

Move farther in and climb the stairs to the next level. Use the torch to burn the salvage net hanging above the stairs. Drop down and crack open the crate. Extinguish the torch, return upstairs and break open the second salvage crate.

Now pry open the door just to the right of the second crate.

Inside you'll find a relic (2/2), a Marksmanship Badge, the second in the Senshi Elite set, sitting on some wooden boxes. Examine the relic by turning it around to see the kanji on the back for bonus XP.

Return to the previous room, head outside and climb the next set of stairs to the upper level, where you'll find the Radio Tower Base Camp and sitting on a rug next to the campfire, another document (2/2) from the Diaries of a Madman series. Use the camp if you like. If you've been following this walkthrough, you should have a Skill Point to spend and possibly enough salvage for a weapon upgrade as well.

There are also a few other minor pickups in this area. From the ledge next to the campfire, ride the zip line down to the roof of a small building.

There you'll find a food cache, more rifle/SMG ammo and the Treasure Map for this area. You won't need the map if you've been using this walkthrough, since you will have found all the goodies already, but it does help with 100% completion.

Jump up to grab the end of the same zip line you just used, climb back to the top end and drop down near the campsite.