It's been a little over five weeks since I installed the solar fan in the compartment behind the fridge (I don't know what happened to the formatting in that post, Blogger!). Right after I wrote that post, I defrosted the fridge for a fresh start. It needed it badly. The very next day I was able to turn the fridge setting down one level and that's where it's been since, and it's colder at this lower setting than it was before the fan install. I'm also not getting any frost build up in the fridge which is awesome considering that normally by this time I'd have so much ice build up as to completely cover the fins. Huge difference.
I'd call this project an absolute success. It has exceeded my expectations and I couldn't be more pleased with the results. If you're on the fence about tackling this mod, I say go for it! You won't be disappointed. And it's a pretty easy mod besides. Win-win!