Rebel Commandos have scout 2 by default. Advanced positions brings them up to scout 3. I might be reading this wrong, but it looks like the last face up card on the wookie expansion might give the user scout.

As there is no 4-speed movement tool, I would take precedence from the Xwing rulling you cannot do a move of a template that does not exist. (In Xwing's case there were some abilities could make a theoretical 4-bank)

It's in the Legion PDF under the "Scout" Specialrule.
You can't exceed Speed 3.

14 minutes ago, BielTanLord said:

You can't exceed Speed 3.

Not with that attitude. ?

Just tack on No Time for Sorrows. That’ll get you where you want to go before the game even starts.