Not to be a "one upper," but I have been wanting one for years. Even have a huge sheet of aluminum to make one, just never got around to it. I tried influencing a couple of people, with the resources to make them, but that never happened either.
I plan on telling them no tray, nor a cutout. As they show a picture without it.
Doesn't to be an air tight seal to improve flow through the rad. The 4Runner for example, has more ducting and stay cooler than mine does. Doing the same activites, with the same engine. Better ducting helps. Even flimsy rubber or plastic would be better there, than nothing.