There are a few things I notice about your bed/wood installation and some other comments from my bed wood installation adventure:
1) the floor wood shown in your photo slides under the bed metal along the edges of the bed. I don't see any holes in your bed lip to accommodate the hold down bolts/flat washers. You can see the bolts along the edge in this photo that I copied from one of the links provided in another response above.

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2) the battery access will need to have some wood pieces added to support the battery access lid. You can see what's added in the photo. I only added one at the end of the batter cover access. Your battery access does not appear to have the metal bracket the supports the rear edge of the battery access lid (see photo).

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3) I suggest you lay all the boards and hold down strips in the bed to get an idea of how it will all come together and observe the gaps between boards to accommodate the hold down bolts. Put the battery cover in to make sure it will fit properly. On my bed, the crossmember panel did not center over the crossmember. I confirmed with others that this is just the way it is.
4) the boards in my "kit" were a little thick and did not slide under the bed metal. I routed a little off the bottom of each board on the end to allow it to drop down some and slide under the bed metal. I failed to check that the crossmember cover would fit such that the top of the panel came out flush with the bed boards. If it doesn't there will be a gap between the top of the panel and the hold down strips. I should have routed out the bottom of the surrounding boards to make the panel come out flush. The strips that cross the crossmember cover are riveted to the cover.
5) there are bolts that go thru the holes in the ends of the hold down strips and attach the boards to the z-panel and the lip of the front panel assembly . The holes will have to be drilled when you position the boards/strips properly in the bed.
6) my wood kit was not cut properly and it took some work and modifications to make it all come together. The cuts for the battery access and crossmember cover were not positioned correctly. If you look closely at my battery lid opening, you will see the "filler" pieces I had to add.
Unfortunately, I purchased the wood kit several years ago off the classifieds and don't remember who I got it from nor who might have been the original producer. That's why I suggest you put all the pieces in the bed and make sure it all comes together properly. If the boards are to long, put some thought into which end to cut off or you will impact the battery access and crossmember panel opening location.
7) the edges of the bed strips I purchased were flared out on one end or some reason. I had to trim out some of the floor board wood strip channel to accommodate the flare. Easy to do with a blade knife. I put the flared end at the rear of the bed. If yours are not flared, you can forget this comment.

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8) suggest that you try the finish you plan to use on the bottom side of a board to see if your are happy with the look.
This part of the project was more tedious and time consuming than I thought it would be. In my case it was complicated by the problems with the wood pieces. Have fun.

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