Going from the Mountain Wilderness to the Bluff without going through Trynton is probably a bit tought at this point (although it has quite a few perks). I usually go to Trynton right after Arnika (it's level of difficulty is comparable to the Umpani area, I suppose). Marten's Bluff is just beyond Trynton and the Swamp, so if you want to go there, you should probably head to Trynton next.
I mean, if you really hate Trynnies, then you don't have to, but it's definitely one of the "early" areas of the game.
The Northern Wilderness is connected to a couple other wildernesses that lead to the swamp and then Marten's Bluff, without going through Trynton (but that's really a bassackwards way to go).
Going to Trynton will also setup an event that helps (though not completely necessary) complete the Mook-alliance quest given by the T'Rang in Marten's Bluff, if you're interested in getting an alliance with them, as well as the Umpani.
So, uhm, yeah, go to Trynton. It makes sense