You would be good for normal forest service roads, but the smaller roads are too narrow and the trees too low. Keep in mind that they maintain the big roads for logging trucks, etc. You will probably have to slow down for the washboards. The overhang is potentially a problem with very long TCs.
However, I was down at Mount St Helens this weekend, and I have to say the paved roads there are horrible and rougher at times than many gravel roads other places.
With my F450, I get 9-10 with 4.30 gears.
Pretty typical forest service roads where I frequent are below although these are the flat parts miles from a paved road.
