Did you add Hydras, they can cloak too, look at LoveLess's Darkness Defense game in database to see what i mean

You should just add the Zerg Larva because they can morph into everything else and it still remains cloaked. The only useful units would be the Hydralisk, Mutalisk, Guardian, Devourer. But you could make hero combinations as well. Two Zergling = Hunter Killer ( Hydralisk )

Yet another brilliant idea made by yours truly!

Uhh yeah I kinda gave up on the dragoon thing again it denys to work >.<.