Add a specialist that conceals number of drillers and/or specialist to other players. Add an element of surprise and achieves an edge on that attacking sub. What are your thoughts?

NO

Concealing the numbers seems too much. It would be ok to hide the specialists by replacing their icon with a question mark. It could be countered with an intel officer.

I think it would be a better idea to say this: "This specialist hides 10 drillers to the enemy when at a friendly outpost. This specialist's presence is undetected by enemy players."

Say you had a sub of 30 + this specialist on route to one of your outposts. When in an enemies sonar range, it would show a sub of 30 and no specialist on board. Once arriving at the outpost (assume the outpost has 0 drillers), then the enemy would see an outpost with 20 drillers and no specialists. Obviously a give-away but if he doesn't remember where your specialist is, or you have multiple subs coming into battle at the same time, the presence of this specialist could be very tactical.