To answer your original question, I doubt bunker spoons would work with either a downrigger or a planer. A properly working spoon would pop off the downrigger or trip the planer too often.
You can, as has been mentioned before, use braid. The trick is to have enough leader between the drail and the spoon, otherwise the weight will kill the spoon's action. I run about 15 feet of 80# test between the spoon and the drail. Although this works, wire is probably still the best method to get a spoon down deep and working properly.
As DBK says, stretch plugs and other deep divers are perfect for braid, but they will only get you down so deep.