I think if you know you are going to have to drop it quickly, and then raise it again, you could rig up a quick disconect pin and use the spinnaker halyard, tied off to the bridle to lower it slowly and hold it back up too. Of course the bridal, spin pole and snuffer are all going to drop into the water as you loosen it all up, but you might be able to keep the crew up on the bow to hold it up until you get under the bridge, then raise it again.
I would love to see some video of this being done however!
You could also put the spin pole bridles and the forestay bridles inside some tubing (plastic, carbon, aluminum) that would go from the tang to the connection point on the pole. With the mast down, the pole would still be supported by the tubing.
