Maker farm i3v rear-mounted cooling duct

After installing a servo, I found that my side-mounted cooling fan wasn't going to work, and I didn't want to add more crap to the front of the hotend. That only leave the back of the extruder as an option and while I've had it in mind for a while, it's a tight fit, at least with the relatively short (55mm) Hexagon hotend.

This fan duct mounts to the back of the carriage using a pair of M5x10mm bolts through the two holes beside the bottom wheel mount. That wheel leads to a somewhat convolute