[MrE]

Dennis, I have a similar age Newell, an 86. Mine isn't perfect by any means. I have two 12v pumps controlled by a panel in the galley, above the sink. From your pictures, you appear to have the wires to control two 12v pumps also. My system is also a combination of mixed materials. My plan is to re-plumb the entire coach with PEX A. Comes in three colors so I can color code my plumbing, blue - cold, red - hot, and white -filtered. I live in Idaho, so more concern with freezing than you would have in Missouri.

Here's a video, why I picked PEX A. https://youtu.be/cTN_OU3yufI

This is the Milwaukee tool the plumber doing our kitchen remodel used that convinced me to use PEX A. https://youtu.be/M9x_D_VxT_Q

I've done plumbing in my house using PEX B, but I always had great access for the crimping tool. My coach doesn't afford that, and I definitely don't want to sweat solder joints in tight spaces to use copper, plus copper splits where PEX doesn't when it freezes.

The Milwaukee tool is around $400, out of my budget to own for a single project unless I can't rent one, but there are numerous mechanical ones for under $100 on Amazon. https://www.amazon.com/s?k=pex+expansion...c94bt2zh_e