Still hanging on at 130mph+... cough, on the "track"
Checked all bolts, none were missing.
Update after 500mi: I will use 3M panel adhesive for the diffuser part to glue it to the bumper. 3M VHB ain't holding due to little touch points. Once 3M panel adhesive is applied, it's stuck to the bumper for life. The tray is fine with bolts, don't glue that part, lol.