Some folks have installed a fan or fans under the canopy skin and cut some holes or slots to provide air flow for defogging the inside of the canopy. I don't know if I'll actually use a fan (or fans) yet, but I decided to include the accomodation for them. Note, most folks install the fans through the canopy skin aft of where this brace attaches. I looked at some photos of where the canopy attaches to the canopy skin and I believe I can install the fans in this canopy brace, then let volume trapped in the canopy brace act like a manifold and vent up along the inside of the canopy
First step was to choose a fan. I chose a Sanyo fan, the part number of which is written on the center brace. It is a 60mm square fan, runs on 12 VDC, and has a locked rotor sensor. They go for ~$12 on Digikey. I'll probably order one or three when I place my next order with Digikey. Anyway, after choosing an appropriate fan, I laid out the mounting hole locations.