That's what worries me - 85 deg. isn't all that hot to get headaches every ride. I do always use sunglasses, but I have troubles indoors on the trainer as well.
All my med tests were normal so the doc is having me try Celebrex, which works really well if I take it before I start a ride. Not really a long-term solution though.
I'll try the jersey wetting, and I recently got some insulated Polar bottles for cold water, at least for the first hour or so. The problem I have with more water dumping is that fresh water can be hard to come by along a ride and I hate to "waste" it. I'll just have to take a full shower when I do stop for water.