Finally got the new bunk in ... thanks for the suggestion of bi-fold doors. That really did speed things up. Front rail is a piece of 1x8 poplar; I cut it down to 7" wide, notched an area for the ladder (to come), rounded over all the edges and stained it cinnamon.
I made the front rail extra tall because my kids have managed to fall out of their bunk beds before. Not sure what I'm going to do about the screw heads in the front - they're sunk in, just not covered. Haven't decided. Suggestions welcome :)
Here it is in the 'up' position. Very tight to the window, but it fits without rubbing against it. You can see the seam where I glued & screwed two of the bifold sections together if you look closely. The third section is hinged. The fourth section will probably become a shelf in my basement.
This is the color I want the whole interior when its finished. The whitewash should keep it nice and bright inside. I haven't done anything with the rest of the trailer yet and it shows ... but this is the quick-and-dirty fix needed to test camp next weekend.