Building a waterproof tray table?

Hi Group,

Here is my idea, does it sound like the right way to go?

I want to make a slightly elevated tray table so when I water and flush I can just let it drain out a hose or into a bucket. I suppose there are two ways to go, either make a waterproof tray with something like Melamine (plastic coated particle board) and silicone caulk -OR- make it from wood and line it with plastic or PVC sheeting (like used in water beds). A drain fitting would be installed. Am I even on the right track here?

These tables would need to have a slight pitch to direct the runoff toward the drain, yes?

Thanks. Mad respect yo. Doc Oc.