Tailgate maintenance & cleaning inside?

Hello- I wasn't quite sure what forum to put this in, but this seemed to be the closest. I have a 2016 Limited CrewMax that I picked up in December. Overall it's a pretty clean truck, but I've found ample evidence that the previous owners apparently spent quite a bit of time on dirt roads, just from the abundance of dirt deposits around the truck. One issue I have is that any time I rinse out the bed of the truck, including the tailgate, when I close the tailgate a cascade of dirty water comes pouring out of the bottom all over the bumper caps, and continues to drip dirty water afterwards leaving dirty deposits. I'm thinking about pulling the access panel off and hosing everything down inside the tailgate as well as I can to try to wash everything out, and probably lube the handle control rods when I'm done. I'm curious whether anyone here has done something like this, and if there's anything in particular I should be mindful of (such as the backup camera)?

 

I would try a pressure washer first and spend some time trying to get all the dirt out. If that doesn't work then remove the access panel and see what's inside. I remember removing the panel on my previous truck and it wasn't difficult.