The boot trays are less useful than they look. They leave a very exposed rear wall of plastic when you fold down the seats, so you can't really leave it in all the time and they take up masses of room when they are out!

Fair point Chris....
Although I wouldn't dream of folding down the rear seats to carry an oversized load in my precious Volvo
Certainly be a nice addition to a 300, there can't be many around, and many probably ended up broken or damaged by the very reason you mention. Searching back a few years on here I see there have been a few offered over the years, but these 'For Sale' posts have virtually dried up now, most of the stuff appears on FB sadly...
Cheers Dave