That's what I used to build mine. The tote has a great little curtain already molded into the lid. It wasn't 100% leak free for me though. After several hours, some water was leaking near the handles. Luckily, that molded curtain made an easy place to hot glue another curtain to. Worked like a charm.
That's a good idea! Just reinforce the lid. I would think a support running across the short dimension would be strongest.
My tote has the pvc in the top....that's what the curtain is attached to.