I agree on the pex, unfortunately on some year airstreams all the pipes are under the floor. Then you have to route the pex through cabinets and closets etc. My 1971 31' Soviergn had the water lines in the heat ducts. Lots of help can be found at Airstream Central.com and Im sure other web sites. Old and new Airstreams have become very popular in the last 10 years. Its hard to find a good bargain on an old Airstream any more.If you're doing a total gut, rip out all that copper pipe and replace with Pex. Much better for something that is subject to freezing temps. When I winterized mine, I forgot to run the antifreeze in the shower head & the copper pipe in the wall burst. So I replaced all the copper when I went in to fix that... & the job was not too bad. Nowadays I use compressed air to blow the lines out instead of antifreeze....works better & is cheaper.