Just wanted to share my work around to save on some labor time. For removal I pried near the 2 rear studs between the parcel shelf and the rain tray. Some careful ‘flexing’ of the sheet metal involved was enough to free first one, then the other rearmost ‘captive’ mounting holes.
I thought about hack-sawing the 2 rearmost studs shorter as this would alleviate the clearance problem but ended up going a quicker and simpler way:
For installation, without messing up all the new weatherstripping and dum-dum, I slotted the 2 rearmost holes on the raintray. An added benefit of doing this is that you can pre-install the washers and nuts on the 2 rearmost studs and use them as guides and a ‘3rd hand’ to aid installation. It worked a treat and changed nothing about the functionality of the rain tray.