To me, Divisadero is a bit of a stretch and 26th Street a huge stretch - even though they may historically be the former boundaries. If the WNP expands, it might be better to do so in smaller increments.
What about Masonic. zig 2 blocks west to Ashbury which joins Clayton/Twin Peaks Bl/Clarendon/Laguna Honda/Dewey? Well, someone else can take it south from there - I'm out of my familiar territory now.