Instead of having one stealth dice to roll to beat a target number, have a stealth dice pool. Each race gets a number of stealth dice, depending on their level of technology... for example EA Early Years get 1, League races get 1, Minbari/Drakh get 2, Shadows/Vorlons get 3. When trying to break stealth you roll your dice, and if any one of them beats the stealth rating of the target, you have passed and may fire as normal. You don't get any +/- modifiers to your roll or to the Stealth score of the target, but...
A successful Scouting roll will add a dice (or add 3 dice if it's a Leshath).
Being within 10" will add a dice.
Being over 20" will remove a dice (minimum 1).
Another of your ships has already successfully attacked the target this turn will add a dice.
Target is in a dust cloud removes a dice.
Target used Run Silent removes a dice.
Etc...
Of course balancing would be required so don't go all statistical on me. I'm just suggesting the basic idea, that rolling multiple dice has a lower standard deviation than just 1, and feels like you have more of a fair chance to pass (even if statistically it's the same). Getting to roll 3 dice hoping for a 6 is more exciting than rolling 1 hoping for 4+, IMO.
A successful Scouting roll will add a dice (or add 3 dice if it's a Leshath).
Being within 10" will add a dice.
Being over 20" will remove a dice (minimum 1).
Another of your ships has already successfully attacked the target this turn will add a dice.
Target is in a dust cloud removes a dice.
Target used Run Silent removes a dice.
Etc...
Of course balancing would be required so don't go all statistical on me. I'm just suggesting the basic idea, that rolling multiple dice has a lower standard deviation than just 1, and feels like you have more of a fair chance to pass (even if statistically it's the same). Getting to roll 3 dice hoping for a 6 is more exciting than rolling 1 hoping for 4+, IMO.