What kind of tray to I need for my combination oven?

Recently I moved into a new flat that has a Panasonic inverter NN-CT54JW combination oven in it. The instruction manual very clearly says that when being used in convection mode you need to use the included enamel tray. My issue is the microwave doesn’t have an enamel tray in it and a previous tenant must have lost it. I’ve tried searching for new trays but they’re all upwards of 60 pounds and I’m not paying 60 pounds for a lousy replacement tray.

I’m wondering if I really need some special enamel tray for this or if I can just get some form of baking tray or even something like this to replace it. After reading the instructions I feel like the only purpose of the tray is to reflect heat away from the glass turntable so as long as it’s covered by something oven proof it should be OK shouldn’t it?