I know that if you are on level 1 terrain with a mech, or level 0 with a superheavy thats level 3, you see over 10+ level 0 heavy woods no problem.
Adjacent woods to a level 2 target would apply, as would the woods for leg mounted weapons. Since smoke is just heavy woods for LOS, it should be no different, unless there is a specific (and odd) superheavy mech errata.
Your talking about seeing over as the higher person. That isn't what I'm asking.
Adjacent applies when looking "down" on something as the only hex that effects you from above.
Looking "up" from below anything in the way is in the way.
That said, Your example of Heavy Woods that is at L0 & mech on L1 is essentially the same as a Tripod. Not exactly, but the top 2 levels are anyway.
Hmm, using that example, I don't think there is any modifier then since if the mech is up at L3 even an adjacent L2 Woods has no effect.
Which is kind of odd since clearly it IS obscuring the lower half of the mech.
Seems like some sort of compromise modifier would be called for but IDK.