yep, just replied on Destins thread, but will here too.
About 10 feet between boxes minimum, they like to not feel invaded, and the thicker over all the better.
Go dig up some old wild shrub in your area and plant in there to thicken the over all look of the pen too and helps with shade for them.
Pen looks awesome, just needs to be thickened up.
Go back to whatever page my pics ended up on and look how secluded the pen looks.
Tree in out area that do great around ponds , grow fast, and help shade and thicken the pen are black willows (grow like weeds here), river birch, pretty much anything you find grown around rivers and ponds , I would just go around the farm, we have a creek here and dig up small ones, by the second season, they were almost touching the top of the netting, then just prun them back.
Willows were mainly what I had in mine.
Then all the fresh trimmings you can get. Once you get heavy planted cover, the need for all the limbs goes down. Also another GREAT one for us to use in them is pampass grass, it grows fast, and thick and they LOVE nesting in it.