It depends what type of a/c you fly, when I fly in the c150 my QFI opens both windows and that cools the cockpit considerably.
A while back, I was flying in a robin HR200 and my FI had the canopy rplled back for part of the flight.
Drinking beer sounds like a good idea
just depends if you want to enjoy you're flying, if you have an a/c that you can "air condition" in the way i suggest.
Makes you envy those who fly Piper J3 Cubs dosen't it?
WelshFlyer.