Looks like you got a great deal Dan, the box looks great and I love mine. I'll leave it to those who know more about the RH / Ambient temp issue than I as I am here to learn as much as anything else.
The one thing I can add is, after many different tries, I ended up getting the "mesh media bags" that people use for fish tanks, bought them online for .99 cents each, I filled those with beads and they are great to tuck in the winador, they take up much less room, you can stack a few boxes on the bottom and top (where you have free room if the beads weren't there) and then just stuff in the media bags.
Example of the media bags (in my cabinet)
