Looking through some other skirmish rules as of late it struck me: why don't we apply some sort of penalty to any Unit with a Done marker?
Alex and Paddy are facing off. Alex wins the Tactical Advantage and scores a 1 on his first Impulse. Alex activates a Solider an sets him running towards cover. Paddy then rolls a 1 on his Impulse. Typically, all things being equal, Paddy would fire at Alex's remaining Solider, the one who hasn't yet been activated. Why? Because he may put that Solider out of action, denying is activation during that Turn.
However should Done Units have their Resolution downgraded by 1 die, then Paddy might have pause to fire at the first of Alex's units - if he was to hit, it would be more likely that he'd send that Solider Reeling.
We might just give it a try.