I'm thinking of making a piece to fit between the rear seats and the hatch opening to make the are flat when the seats are folded.
I am sure this has been covered but my search has not returned any appropriate finding.
Anyone willing to share?

Thank You

 

There are a ton out there that have been made with various materials: wood, plastic, metal, even foam rubber. Try searching for "boot box" and you might have better luck.

 

PM me with your email address and I will send you some pics of a project completed last year.