I just picked up my 2021 ES300h but after reading this thread I hung onto the spare wheel from my old GS300 as it was 18" the same as the ES. Turning the tool tray upside down I marked the out line on a piece of plywood I had left in the garage to cut the shape and added a couple of short battens on either side to prevent the whole thing dropping too low. A bit of sanding to shape the battens and make it fit flush and here it is. Just need to buy a can of matt black, give it a coat or two and it will be done. I just put all of the items from the tray loose in with the spare wheel with the jack across the center.
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