Despite the soaking, I regrouped and moved ahead with building the 5th wall.
Assembly went fairly quickly, however I’m starting to run out of wood(!). I had to scrounge around a bit to find the wood for the crossbeams.
A bit of glue and screws later, it was assembled:
Then I made sure it was square (measuring diagonally from corner to corner) and then nailed on some scraps to keep it that way until I could install it.
I ran out of time to install it, so that will have to wait for next time.