I would not get overly concerned about water being on, modern RV'S have used pex lines for many years now. It's the same stuff used in homes. Now that I'm retired I wish I had done what your contemplating. When I started working home computers were just being introduced. I would check however to make sure your frig is not on a modification list for a burner shield at be installed and temp limit switch. You can go on line and check the serial number. The modification is free. Your Terry Quantum is a good trailer, if you keep it maintained roof maintenance is very important you should get several more years out of it. RV'S are a depreciating asset. Good luck with your new adventure.
Forgot to add I have a seasonal summer site. I enjoy the company of people at the campground like minded adventurous people. I bought a scooter to run to the store and explore on, about 60 mpg and fun. Bought it used for a very good price 500cc Kimco xciting.
You can build a good nest egg and upgrade when you feel the need.