Tundra bed composition

I’m working on removing some rust from the bed of my truck in preparation for linex.

I sanded down through the paint and then the silver metallic layer started peeling off and there is a black layer underneath.

I’d like to get out all the rust but I definitely don’t want to put a hole through the bed. I thought it would be metal all through like the tailgate. Is this place layer metal? It seems to also have some rust. See pictures.

 

that's where there was deep rust. you will have to get all of that clean or the rust will come back. at that point you'll have to cut that section out and weld in new steel

 

It starts from underneath, better take a look before you linex the bed,

 

There is no visible rust underneath. There seems to be a black protective coating.