Let me start by saying that the entire water system was freeze damaged, so I had no issues regarding saving any part of the plumbing. Second, let me say that I've never found the 70's models to be particularly well-designed when it came to using space wisely or "dressing" the systems to look nice. Third, the mid-bath and kitchen in my Sovereign are together on the curb side, but Airstream insisted on putting the water service in the standard location, on the street side rear end, which forced them to run a pipe under the floor to cross the trailer. This pipe is highly susceptible to freeze damage in that location, not to mention durn hard to drain.
Here's the pee-poor layout under the cabinets. Note the totally inexcusable routing of the vent tubes straight through otherwise useable cabinet volume.
So, new water system, totally. My previous three refurbishment projects used copper. However, my latest Fine Homebuilding arrived with a glowing report on PEX (right after I bought the copper, but hadn't started work, yet). Ooooh, good excuse to buy new tools! I wanted the slickest installation I could do, so I elected to use crimped fittings. You must have a crimper (can be rented from local plumbing places--about $110 to purchase new). A tubing cutter isn't absolutely required, but when you're making very small adjustments to pip lenghts, on the order of 1/8", you can't do it any other way. After cutting PEX with a razor knife, about 2 cuts, I can't say enough for the ratcheting tubing cutter (about $35).
I could find many parts locally, but not the swivel female 1/2" FIPs or the valves. So I started with what I could locally, including the red/blue pipe, and ordered the rest over the web. Very good service out of PEXconnection in Oklahoma City.
Only one connection was difficult--the toilet. It has a 3/8" FIP inlet. I couldn't find one of those that (1) was 90 degrees and (2) had a 1/2" compression pipe fitting on the other end. I could find one with 1/2" tube, which is 1/8" smaller (go figure). But a short roll of tube at Home Depot is $35, ack! Local plumbing supply sold me a short piece of 1/2" tube, which makes a nice toilet connection with a 3/8" to 1/2" sweat insert.
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