I have bought two Airstreams and returned them to service in the past 14 months or so, one I did a lot of work to, the other a little, but on both of them I replaced all fresh water plumbing with PEX.
It seems like a big project and it kind of is, but it can go quick, quicker probably than repairing badly freeze damaged copper.
Now I am going to say something that a lot of people will take issue with. You don't have to fix everything right all at one time. You can do things in pieces enjoying your trailer in between.
Leaking pipes, safe electrical, safe towing, safe gas, and and major structure issues must be dealt with however.
We turned this trailer in less than 14 work days from start of work to functional and off to New Mexico.
In this 14 days it got all freshwater plumbing, this took probably two days including taking apart for access as needed and going back together.
I didn't have to take too much apart.
On this quick and dirty build I ignored some bad floor in the back of the trailer, and a little bit of bad floor in the front left corner.
It is my intent to do the trailer "right" some time in the future, but what I have done will work for a few years.
IMO, the condition of your Arosy and the trailer pictured are comparable.
The flooring is peel and stick, quick, easy, cheap, and DONE.