Because they are trying to coordinate 3000 guitar players you have to either play acoustic or electric with a pignose amp.  After much deliberation I chose to bring my Greg Bennett Design Les Paul copy and bought a new Marshall MS-2 micro amp.  It requires a 9 volt battery and sounds pretty good considering it is fits on a belt buckle.  It even has overdrive... which will sound good on Purple Haze.  Off to wine country tomorrow, but on Saturday we'll be heading to the Haight Ashbury district where I'm sure it will be crazy.  Lots of pics to follow.