[Gigermann]

Hmm…

Simple solution: -2 "Check Target" penalty to exclude a potential target or hex would seem reasonable. For simplicity, I'd say you can exclude any number or arrangement (not worry about "patterns" and whatnot), with just the "distraction" penalty of having to be sure you're not hitting something unintended. Should probably include a chance to hit the excluded target anyway on some miss, maybe 5+.