Lid for 13 x 9 baking dish

Hi I have the Advantium 120 and when used as a convection oven, I don't know how to cover my 13 x 9 baker. You can't use foil and I can't find any type of lid for a 13 x 9 that would be safe in the convection oven. If it's not covered, it splatters all over the top of the oven when I use it. I have been placing another 13 x 9 over the top of it and then it falls off when it's turning, etc. Anyone else have a suggestion?