My original Panasonic went bad on my 2008 v6 and I replaced it with a Caterpillar grp 31. Only thing is it has threaded top studs not posts. I bought the thread on post adapter and hooked my stock wires to it. It's a little taller, and with the lip of the tray and the extra terminal/battery height, I needed to remove the tray to get the hood to shut. The battery is still sitting about 70% on the flat area and the stock clamp secures it just fine. Given that the battery is made for vibrating around in heavy machinery, will my setup without the tray be ok? Or am I writing a recipe for a battery case crack? I don't see how a flimsy piece of plastic provides that much more support than the heavy duty base of the battery, but I don't know.

Tray is just there to catch any spills from battery but provides no structural support. Since it seems that your Cat battery is AGM you don't have to worry about spills ever again.

I just learned something new! Thanks!

Yes you do

Sure you do... Its serves better.