I saw this thread a while back during my last trip in the 4Runner. I wanted to post a picture of my current solution but forgot to do so. Finally here is ma solution.
I am still using the OEM cargo cover which did leave some space in the front for the seats to recline. But, in order to maximize the cargo space, I always leave the seats in the up position. The cheap solution I use is adding a simple black bed sheet below the front of my WeatherBeater cargo mat and wrapping it above my luggage. It covers the front of my luggages but also the back. The gripping pins of the WeatherBeater cargo mat prevent any slipping of the sheet. Simple and effective.

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2016 Trail Edition Classic Silver Metallic with KDSS, sunroof
ToyTec BOSS lift, SPC Light Racing UCA, RCI sliders, RCI aluminum full skids, RCI Cat Guard, Eezi-Awn K9 2.2m, BFG KO2 275/70R17E, FN Wheels f(X) Pro, ARB Breather kit, Husky WeatherBeater Mat and Cargo, XPEL window tint, 3M wrapped hood
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