To me, that looks like a piece of PEX coming out of the camper, not vinyl tubing. It's white, a bit thick, and the band clamp that's holding it onto the valve is commonly used with PEX, similar to what Bill posted a picture of. It would be easy to tell -- a piece of vinyl tubing, even with age, would still allow that valve to wiggle side to side. PEX would not.
What I'd do is try to just get that band loose. Sometimes it's fastened on there by the 2 ends of the clamp latching onto each other, and even then pressed into each other. If so, you might be able to break that connection loose with some needle nose pliers, and the band will then just peel off. If the band has a bulge protruding out from the tubing, like the one Bill has pictured, then just cut the bulge with some heavy wire cutters or something similar.
After the band is off, if that is indeed PEX coming from the camper to the valve, that is more than likely the water heater drain. Easy to verify just by looking under the sink (and would be consistent with PEX coming through the floor to that valve). And if that's the case, then draining hot water from the water heater through that line will soften up the PEX enough to just pull that valve right off.
As to a new valve, I would use a "Flair-It" fitting -- something that looks like this (not sure if this one is the right size:
https://www.amazon.com/Flair-16892-P.../dp/B000BQT694
These simply slip into a piece of pre-warmed PEX, and then the compression nut tightens the PEX over the fitting. Easy to remove, too. They work great, and it looks like there's some sort of Flair-It fitting below your valve. What is that?
Alternatively, you could use some sort of Shark-Bite type valve. Plastic would probably be preferable in that location. Something like this (again, I have no idea if this is the right size):
https://www.amazon.com/Speedfit-Conn.../dp/B003YKF2F6
These would be slightly easier to install vs. a Flair-It, but probably slightly more difficult to remove because you'd have to get a tool in between the camper and the valve to remove it. There are some small tools, but you'd also need to be applying downward pressure on the valve towards the ground to remove it.
Dave