love the simplicity of your shutoff valve.
the only problem with that is the wear and tear on the edge and it cracking over time…and a chance of a puncture if metal fillings get in the line…and then you have a major water issue.
the PVC valve…I used a copper ball valve will last a long…long time…will almost last forever…
the only problem with the filler you have…is if it sticks over the top of the slats at all it will rub on the metal sheet…what is the splash like?