Sometimes a character may want to fire at targets they have no fix on whatsoever. In these cases, allow the attacker to make a Shooting roll at -4 as above. Should he hit, the target may make a simple Stealth roll to ignore the attack (it misses). The Stealth roll is made at -2 if the attack was made with a RoF of 3 or more.

Savage Worlds Deluxe Edition p. 76