Here you see a 40mm Rat Shack fan. Thinking about installing four 30mm fans, two over radio and transponder and two over Dynon D10A. Figure they will help with demisting as well.
As far as GPS antenna, Wayne and I tested GPS reception. We covered antenna with fiberglass (both epoxy and whatever ester instrument module is made out of), Plexiglass and firewall phenolic stuff. It degrades performance a little, but even covered with all this stuff as long as a ground-plane was below antenna, reception was a tad better compared to the finger sized antenna connected direct to 296. Will install GPS antenna below top of instrument panel kinda sorta above Dynon D10A.
Y10-02-14