Installation of bedcap shims supplied for 2018 Tacoma

I have a question. I recieved my Diamndback SE cover for my 2018 Tacoma A.C longbed today. Was going through the instructions and started later this evening. Wanted to ask a install question...

My instructions came with a requirement that I was to install 8 shims underneath the bedcap rails of my Tacoma. I did so, and it just doesn't seem right, at least from eyeballing it. Their is a definite bend in the middle of the bedcap rails after I installed the 8 shims on each side, IAW with their instructions. I sort of expect that the shims will be compressed as I install the center panel, but this is like really pronounced.

The pictures in the instructions don't exactly mimic the actual physical bedcap mounting holes in my bed, as I would expect. There is a difference in how they are situated as opposed to Diamondback's install instructions. I used all eight shims on each side as best as I could IAW their instructions.

I took pictures of the instructions and a pic as best as I could of the left side bed cap, with the bulging mid section due to the shims.

 

I kept following the instructions. I'm not sure if there was a bulge. After placing the midsection and clamping it to the rail--no bulge that I can remember. You retighten the midsection after a week.
PM if you need more advice.

 

I did complete the install today. After clamping on the center section and working with the rest of the cover, the gap has disappeared everything seems to be sorted out with it.

 

Hopefully I can wake this thread. I just purchased a "new-to-me" Diamondback HD for my Tacoma and am going to install some improvised neoprene rubber shims. Can anyone give me a thickness that I should aim for? I'm thinking 1/8" should suffice. Thanks in advance.

 

1/8" may be too thick. Take off the plastic rail and measure the depth in the area where the center DB rail attaches. Rubber -not neoprene which will compress. Want to use something dense.

 

The stock shims from DB seem too thick and firm to me but I need to order another pack before I install. Hopefully they will compress down, as they seem to have for the OP.