[Suicide Junkie]

What if you were to get creative with an treaty?

Organize with one of your friends to have a ship from both your races in the sensor-blocking sector.
Then sign a treaty which gives you full view of the other's ships but still lets you fight.
Once combat starts, the spies should be targettable.

The main problem would be if you only get the sensor readings from the ships, and not vision of the cloaked ships themselves (as it was in se4)