The way I did mine was with no wood in the bed I put the six bolts holding the bed on to hold it in the proper position ,made sure the bed was square and using a pencil made intersecting marks were the hole goes on the side of the box and back brace ,front panel. I then put the one side board in so you have to take out two of the bolts drilled the back hole put the bolts back in checking square frequently.There are only two bolts (the back two that hold the bed on the truck until the wood is installed so being careful keeping box square before drilling .Once the two back bolts are in and drilled i moved up to the next hole using the mark on the bed and you can see from the open floor on the side were the bolt hole is and can mark center to drill the next hole .the last hole at the front is on the 2nd board and also can be marked by the front panel and from seeing the hole from the side to mark centre. I made the disc depression by marking with pencil and using a dremel tool to grind out to make it flush .Years ago I used the forester bit and it worked better but I could not find it .
