Here's how I converted my wagon to a van layout. Removed second and third rows, removed center bracket for second row, added plywood to span from back of first row all the way to the tailgate, and topped it with rubber matting so things don't slide as much.
https://fordtransitconnectforum.com/topic/4109-converted-2015-lwb-wagon-into-a-van/
Most of the photo thumbnails aren't showing now, likely due to the forum changes over the years. But if you click on the markers they still take you to the photos. If you scroll down about halfway through page 1, you'll find download links to some pdf files with dimensions of the cutouts in the plywood for an exact fit. If you just want to skim through the photos, here's the link to the album.
https://fordtransitconnectforum.com/gallery/album/160-2015-tc-lwb-wagon-modifications/