I've never heard of The Red Hat Society before, but if I was in your area, lambikins, I'd be happy to accompany you as a "pink hat" friend!
The group you found sounds inclusive and fun; I am also a fan of costume play (I used to do Renn Faires) and have always had a particular love for hats. Plus, anyone can rock red and purple if they have the right attitude.
I know what you mean about the difficulties of getting all your friends together for group activities. It's near impossible these days, at least in my circle, where everyone seems to be scheduled up the ying yang or in far flung places. Of course, I love seeing my friends one-on-one too, but sometimes I do miss the energy of a group dynamic.