I ended up calling Eagle. They said they use Grade A pine, untreated, and so I did too. I gave it two coats of Thompson's Water Seal, spent a few few minutes with a pneumatic stapler and I'm in business!

Bunks
 

I did mine WAY different. I did not wrap the bunk. Wrapping retains the water and rots the board. I used DF from Home Depot. I routered all the top edges to a half inch radius, I then glued indoor outdoor on the top flat that contacts the hull. Used liquid nails.. 6 years now and still looks the same.

Pics and material list?

+1 Just did mine too. Local trailer builder confirmed untreated wood...said treated wood has chemicals that in his experience eats up the carpet in just a year or two. I was also told expect 8-10 years on the boards, at the most and I'll be at it again. We shall see, right?

If you plan on keeping the boat for a long time use Trex. Will last forever.

I was thinking dont they sell the boards int he composite decking material, if they are the same size, those would last forever you would think.

I know they make 2x6.

I know that, I thought I have seen 2x4 as well. Im sure you can find them online. Triple the price but no rot and no replacing again

Stapling into Trex and getting the staples to hold might be an issue. Don't know never tried.

Glue it down with fiberglas resin.