OK, if you plan to put some screws into foam, like XPS, you'll need some meaty screws. I had a feeling the regular screws I put in for the front grill block wouldn't last, and they didn't I used these Wall-Dog screws instead and they bite in there hard.
Also, ordered 40x 1" x 3" solar cells (0.5v and 0.68a each; 0.34w). I'll use 28 of these in series to give me about a 14v, 9.5w system. This should easily power a couple of 80mm fans, but also give me the option to trickle charge the battery (with a small charge controller). Should be an interesting little build.