I was reading back a little insted of a wooden box for the battery perhaps a cooler would be better, it would help keep the battery warm in the winter, and being somewhat air tight would help keep any out gassing under control.

I would be interested in knowing how much voltage drop you have from the PV to the charge controler. I am in a situation where I will need to run about 100' between a PV location and where my battery is. I was thinking about going with #6 or #8 wire but if I can use #10 it makes it even more pratical.