On the Idaho: A Climbing Guide website, we found the description of the route that Tom Lopez and Brian Wright took up Triple Peak. We followed the same route in August 2012. We thought that a Class 4 rating was appropriate. Carl [Hamke] and I nearly always rope up on Class 4 in Idaho because we do not trust the rock (a politer way to say that we are wusses).
That said, we thought that the climbing up the initial short wall was straightforward with reasonably solid rock and good protection (one short pitch). Beyond that, the traverse past the keyhole had some exposure and the climbing was easy, but the rock was quite shattered with some big balanced boulders. We ran the rope out and I remember finding protection for a belay at a wall. But when we down-climbed, the rocks that I had been standing on for that belay collapsed. Your “overhanging road cut” description came to mind as we moved down to get into the dirty gully (we ran the rope out again up the gully) that led to the ledge and the gentle talus slopes below the summit.