Do mortars, which have the rule ignore cover, have a -1 to hit modifier when targeting stealthy units?
Nope - Stealthy and cover are separate things so they take the -1 . Also don’t forget its -1 to shot an individual too
Just to clarify, yes they do get get the modifier?
Stealthy and Cover are different rules. Mortars take the -1 from Stealthy as they only ignore the Cover modifier.