Front bed rail...topper thingy?

I bought the truck (2013 DCSB) used and it came with a Leer camper shell already on it. During the winter, I noticed in heavy rain that the front left bed would leak a bit. Noticed that the foam padding seal was cracked and broken so I figured wait until summer then take the camper shell off and re-seal between the truck bed and shell. No biggie at least the actual topper wasn’t leaking, just a spacing/gap/seal issue.

Summer is finally here, I’ve had my topper off for a few weeks now and need to put it back on. Hop on Amazon to look for a decent roll of fresh rubber 3M strip but when measuring my bed I noticed the front rail is “missing”?

I believe that the front part of the bed doesn’t come with a rail molding but please correct me if I’m wrong. The sides of the bed have the plastic rails on top and there is a 3/4” gap from the sides of the bed to the front so I’m assuming that’s why my topper has been leaking in the front.

Any suggestions for getting the bed flat so I can put the Leer topper back on? I figure if I buy 20ft of 3M rubber sealing strip, I can double up on the front?

I’ve tried to attach pics for reference.

 

I have a 2013 dcsb and confirm the front bed edge is lower than the side rail caps. As for sealing the gap I have no experience as I have no cap.

 

i think you need something like this

$16 ESI Front Rail Seal 6ft EPDM Rubber

https://smile.amazon.com/Front-Rail-Seal-EPDM-Rubber/dp/B00C0WVV72