Ahh sorry. I misunderstood what you meant. They're not modular. I thought you meant remove one of the actual drawers, and not the entire half.
If you check my build thread, I started building it modular and the design is pretty easy. It did bolt to the 3rd row using J bolts from Lowe's.
I scratched the initial modular design though because it was a lot of excess materials and work to make it all work together. You also lose significant space in each drawer. I really thought about it and couldn't think of a single scenario where I would need one drawer and one 3rd row. If I need the 3rd row, I likely am not camping or anything that requires a drawer since I have 6 people in the vehicle.
You can get a lot of width building it the way I did. If you look, I staggered the front and middle vertical supports to take advantage of the extra width around the wheel wells. My actual drawers are nearly wheel well to wheel well in width.