The post guys have a legionaires style lycra cover that slips over their helmet. The Anti-cancer shop had one too which my friend bought. She found it inhibited airflow through her helmet. On the 50kph last year she got hotter and hotter instead of burnt. I've not seen many people with them and I think that is why.
I had lots of sunscreen on and just kept putting it on my face. Forgot the legs though, so my calves got a tad singed. My helmet has a small peak at the front which shades my eyes a little.