Interesting proposition, Paul. I don't see why they couldn't be made welcome and included. But, as you say, it would likely increase the workload and effort of those who do the history walks, research/write the new neighborhood histories and keep up the site, etc. If you were all willing it might be quite interesting and fun.
Where are the official boundaries now? Or the unofficial boundaries? Arguello, Stanyan, Presidio? Dewey...? It can get a bit muddled. And if you look at a map and run a north/south line through the city, a case might be made to include the Presidio, too.
(I couldn't resist the last part - and I don't think anyone but me would care about that.)