Good question. Twofold approach I think.
First, essentially what General Chang did for his own Bird of Prey - invest research and Romulan diplomacy until we can get ahead of the sensor curve on cloaking technology again, and fire while cloaked. A major strategic asset of the Klingons is their willingness to do chaos raiding with lots of light ships, forcing their enemies to spread themselves too thin trying to defend everywhere at once. A Chang BOP can do stealth escorts behind enemy lines, engage Excaliburs in one sided duels, and leave the fight if it turns against them. In a fleet battle they can also do undetectable strafing runs to support other fleet elements.
Second, essentially what we're building now - a heavy tank that can survive your dps long enough to land solid shots on a lighter, faster opponent. A Klingon sensibility means heavy forward and rear weapons, but add on disruptors to keep up constant pressure.
edit: Group them up. So a tank that can take Excalibur fire for a bit while 2-3 cloaked Birds of Prey take invisible pot shots at the Excalibur, who can't effectively split its attention to respond. Keeps it to 'cruiser and escorts vs cruiser' rather than two to one odds, or three to one if the Fed captain is having a really good day.