Consider using a space heater to really dry out the wood. The bleach mixture spray is a solid solution after it's bone dry. If you had 3" of water (Thats a LOT of water), your likely to have had water seeping down much farther than you can see by removing the headboard and trim.
I googled your model and see that it is a class C bunk you are talking about. I would want to inspect the wall at the edge of the bunk and the floor below it also, just to make sure I got everything dried out and treated. Just my two cents worth. Would hate to see you fix the leak but still have water damage and your wall or floor rot or grow mold.
2020 Chevrolet 2500 LTZ, 2019 Forest River Wolfpack 23Pack15, 2014 EZGO Golf Cart.