The Sunder with the Tachyon Lance actually works alright-- if you assign it to a fire support waypoint with other LRM platforms like Buffalos, Condors, whatnot. My main issue with using it in campaign is wasting a 30,000 credit weapon on the SUNDER, and risking it in combat. It literally costs more than the ship.
The Sunder only needs one weapon, the Tachyon Lance. And it's the safest ship in your fleet to let mill about and do what it will in large fleet actions. Why?
Because it's not a fast ship compared to the Medusa, so it shouldn't be on your front line but rather in the first reinforcement wave after you take the closest objectives.
It's own range will ensure it will never get to close to anything dangerous as it will not be getting the Engine Boost due to firing it's weapon.
It's cheap on fleet points for the amount of firepower it brings to the fight.
And if you are really concerned about fighters you can outfit the 3 turrets with PD mounts and place Swarmer Missiles in the missile slots.
Besides, one word describes what happens to a fighter that get tagged by a Tachyon Lance. Popcorn.
(Also helps that I haven't started a world where the first convoy dropped 3 of the things in the station, no mods
)