Well I have seen bald pro-cyclists with tan circles on their foreheads from where the sun gets through their helmet vents. My hair covers enough of my head that I don't have a similar problem.
There are a few companies that sell summer helmet beanies made of thin wicking fabric. You could try something like that. TE carries them. They're low on inventory right now as they haven't moved to the new warehouse yet, but I would expect them to get new stock in soon for the spring and summer. Another brand that TE does not carry is Head Sweats.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles