For sure. I carry some 2x6 pieces in the MH. Last time I needed it was on collapsing sandy soil that was easily turning into dust but called offroad recovery to pull me out. When rear drive duallies are burying already, getting the jacks under the axle might be a no go that's why I wonder about frame points which are higher and can be accessed without crawling under, when your tail pipe is already close to touching the ground its easier to dig space outside on the edge.
As to 2 3 ton jacks....is it more or less stable to use one 6 ton jack versus two 3 ton ones? I'd think having single point of failure with all weight on it is worse that having 2 jacks in play? And do I place them right next to each other under axle? (I wonder if this can stress the axle too much having one jack too far towards its middle, the official lift point is right next to the end)