I modified my tool tray, cut the triangle area out and put steel screen in there. Works fine but I also drilled some holes in the air box lid. The air cleaner being a triangle is smaller than the air box cover by enough so as to be able to drill holes around the outside and the air filter is still applicable. I bought seconds of both pieces to replace them or send with if I ever sell one of the bikes. 
the mods worked fine. But, I was able to drill the holes in the air box lid on the second 400 without having to modify the tool box cover. I’m sure people may be concerned about the air box having holes in it but it’s the easiest piece to replace and it’s effective! My 400s are queens so they’re not going to be out in any rain while I own them.