Home Depot sells the clear plastic with no markings. I have the same interior color as you, and while I don't need to protect the same area as you (yet!), I used it to individually wrap the rectangular covers on the tail gate (to protect from staining when loading boxes, strollers, etc.), and it has worked well.
2010 LX570 - Black Onyx/Cashmere (El Jefe)
2010 LS600hL - Starfire Pearl/Ivory-Black Two-Tone (Maximus)
Gone (but not forgotten) Lexi...
2008 LS460L Black Sapphire Pearl/Black
2007 GS350AWD Obsidian/Black
2004 GX470 Blue Meridian Pearl/Grey