I think I found the solution to the problem of being suspected of pervery at WNBRs. Talk to people. Say a few words. I don't mean go and chat up the pretty girls

I spoke to loads of people in London and Brighton last time and had no problem whatsoever with any of the participants. But I did have people frequently wave and spontaneously pose later on when they recognised me from earlier.
It quickly became obvious to me that most of the riders dislike people being surreptitious or overbearing. The more overt your equipment, the better, I think

It's also good to have a chat with the stewards. The riders see you doing so and I think this also puts them at their ease if they later see you snapping. Always have respect for people's personal space. Assume nothing.
The more pushy people were, the less they got. Brighton in particular was a great day. It's not often you have 19 year old identical twins insist you g
o and take pictures of them and their friends. I obliged, of course. Would have been ill mannered not to
Agree with Pedro - at the big rides, your first instinct is to run about snapping madly. That's pointless. You'll get good shots. And you'll get loads of walkthroughs and other frustrations. But just go for what catches your eye as if it were a carnival or any other event.
Remember that this is after all primarily a protest and awareness raising event. Wearing a pro-cycling or pro-green issues tshirt is a good idea. Something this simple marks you out as a supporter of the cause. By going about discussing the various issues with people, I found myself getting loads more shots than I had previously. It wasn't a ploy, it just happened like that and you find yourself understanding why people do these rides a lot better.
Of course, there are those who just like to get naked in public and fair play to them

But I noticed over and over again that the people who were there to just ogle people and take bum and boobs shots got a very frosty reaction, as you'd expect really.