Some thoughts.... the Argosy's are prone to rear pipe leaks. There's a space where the wood is cut away for the black tank that subjects the pipes to freezing. The hot water tank is also subject to freeze damage.
However, I will tell you that I had leaks from behind the shower, under the rear sink, under the rear pullout bed, and by the freezer. It was easier to pull it all out and start over for me.
Any chance you might want to do it yourself? Plastic pipe is not hard to work with (Pex). See http://thevap.com
for some ideas about easy, no tool fittings that push together.
I'd also save the copper. We've had stories of lamp posts being stripped of their wiring here in the NW for scrap.