Here is a little of my setup and just yesterday I added a single grate as a test. I was thinking of having 2 levels, sorta like that link to Sari's DIY one, however they would enter on the floor level then jump up the to the higher level and have to walk a bit to the box. This would get 2 full lengths of grates for them to walk over. Perhaps overkill though.
Going to test this set up oiut for a week or two and see if any improvements then make it look nicer