I was getting a lot of water and snow up between the tailgate and the bed. Also through the rear stake pockets. After looking at the options of stick on seals, pipe insulation and issues with the auto tailgate not working well after install and not really finding a whole lot of information on other options I came up with the following and thought I would post it. Super easy, doesn't bother the tailgate opening and closing like normal and works really well. Can be really cheap if you have scraps of some kind of material laying around. I have the backflip fibermax bed cover as well.

1. Stake pocket plugs off of Amazon, they fit and look perfect.

ES ENGINEERED BY SCHILDMEIER Stake Pocket Cover Set for 2019-2023 Silverado/Sierra (Set of 2) NOT 3D Printed

2, Super heavy duty landscape fabric to bridge the tailgate gap.

I ran about 6-8 inches under the tailgate cover, removed the screws, put the fabric under and then put the screws back in. Closed the tailgate and got the fabric situated and marked where I wanted it, opened the tailgate and then cut everything to fit. I went the full bed width with the fabric and ran a few feet up in under the bed mat so everything would stay nice secure and in place well. So far it has been completely dry and works great.