Whoever put on the previous tub spout soldered a coupling onto the existing pipe to extend it since it was way too short. Removing the spout also removed the pipe back to the coupling. So now I have a coupling about 1 1/2" out from the wall, which has an acrylic surround, that I need to extend a few inches for a new tub spout. Any advice on soldering a new pipe into an existing fitting that's very close to a plastic surface? Is it a hopeless situation?