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

I have a very similar Panasonic convection/microwave oven. The direct heat from the top element could damage the glass turntable or the plastic wheels it runs on, as you suspect.

There are two situations here:

• Convection (or grill) mode. This doesn't turn on the microwave, so only protection of the turntable/wheels is needed. Just use a big enough round tray to cover the turntable. Sizing may be a little tricky as there's very little margin around the edges. It does need to rotate or the food won't cook evenly - a lot of the heat comes from the top at the back.
• Combination mode. Here the heating element is used along with (reduced) microwave power. There's a little more chance of incompatibility but it's actually pretty low. I've used a smaller version of what you link on top of the provided tray, with no problems at all, when I forgot to defrost what I'd frozen in the dish. You'd be more likely to have issues with dishes containing pointy corners (when things spark in microwaves, that's where).

The biggest safety issue with metal dishes in microwaves is food not getting cooked properly in all areas because the metal blocks the microwaves. For that reason it's good to get something with low sides if you plan to use combination mode, so the microwave heating is as unrestricted as possible (even this is probably more of a food-quality issue for most dishes). Especially in an inverter model, if you do get sparking, it's more likely to trip out the electronics than to cause a hazard; on my Panasonic (I selected the wrong mode for something in a foil dish) that means just turning it off at the wall for a few seconds then back on. As this one isn't yours, you should be a bit more careful to avoid doing this in case it breaks.