The bed of a Toyota Tacoma, between the wheel wells, is not 4 feet wide. Instead there are cutouts in the bed liner to insert two 2×8’s or two 2×6’s and place the plywood on top.
If you then place a milk crate on the tailgate, the tie downs at the rear of the bed will securely hold the plywood in place. (Milk crate is black, so it’s a bit hard to see). Thanks to this video for the idea and help with tie-downs.