How to fasten new valves.....
When the shark bites
Into PEX dear
Connections. are made
When the Shark bites
into Pex Dear
Water leaks. Go away
Ok so you likely guessed the tune
The easiest way to connect to PEX is sharkbite connectors (Lowes/Home Depot/Menards/ Most plumbing supplies)
Cut the pex "Square" push on till it stops. give it a bump (About another quarter to 1/2 inch) and done the other end of the sharkbite is 1/2 Inch IPT thread to your valve
There is also a type of connector you can find at most RV stores called a "Flair It" you slip a nut over the pex then use a tool to slightly expand the open end shove the Flair it up into the pex and tighten the nut down on the connector.
I like the sharkbite's myself but have both in this RV.