As long as the road are public all rules of the roads apply (no exceptions give for rural farm roads). Secondly, the steering axle is not on any sort of suspension, the axle ariculates up and down about a center pivot point maybe an 1 to 1.5 up work movement from level position, the axle beam contacts a welded on mechanical stop. The stop is there for stability rating compliance.

Industrial truck of the same lift capacity are much narrower and shorter than those big tired machines you are referring to - al lthat means the will turn over faster, expesically on any curved (or crowned), banked surfaces.

In three words, "Don't do it" there are a lot of PL lawyers looking for a big pay check.