Re: replacing carpet on trailer bunks
Surprisingly, most all OEM trailer bunks don't seem to be pressure treated?
My guess is that they just don't figure it makes much difference. Most factory bunks I've seen have been pretty loosely wrapped, with no glue at all and by far not near enough nails or staples. The last one I had new didn't even have stainless staples holding the carpet on and the carpet only barely covered the sides of the 2x4 bunks.
When I make new bunks, I use either redwood, cedar, or PT wood. (I'm leary of the PT with an aluminum hull). I spray the board and carpet will with contact trim adhesive, and roll the board onto the carpet, using stainless staples on the underside. The wood is well coated with glue, which no doubt helps preserve the wood, and the carpet I use is a waterproof outdoor carpet. The first one I did this way is still as good as new many years later.
I would suppose that any good outdoor carpet would suffice, and if your using PT wood, then just stapling it down should do fine. What I do is overkill, but I tend to do everything that way.