I use a similar "dump" filter design on my big tanks (because they're not drilled). It's a simple, efficient, effective and easy-to-clean design. Been using them for years.
Best thing to do is to put the pump(s) in the tank and plumb them to spray water into the rubbermaid or whatever container (I use clear rubbermaids) that you're using (on top of the tank).
I use 2x4s to support the filter (on top of the tank).
Like a sump, you can use a filter sock or fluff or sponges or whatever on top for mechanical filtration. I have a plastic tray of fluff and then a piece of Poret foam on top of a bunch of bio balls, scrubbies, etc. in mine. Stack a couple of pieces of egg crate (light diffuser) on the bottom of the rubbermaid to ensure that it doesn't get plugged by a bio ball or whatever.
The water returns to the tank via gravity...so make sure to drill SEVERAL good-sized holes in the bottom of the rubbermaid to ensure that the filter can drain adequately. If in doubt add another hole.
Matt