Going on three weeks on this tugboat and I am dreaming of getting home to my four trak and recording some bits and pieces of Dead tunes to practice along to. Going to record some rhythm along to a click track, then bass and lead. I have been studying modes a lot, all keys and all positions; but I have never tried to play any Phil lines and frankly always found his style kind of intimidating. Anybody have any suggestions or general principles about how to try and approach his bass lines?
Listen to the John Cage recording "Four Walls". Make sure you know your scales and chords (doublestops). Listen to Phil...a lot! Most music groups make the drums and bass the "floor" off of which the rest of the music is played. In jazz, you'll find the same thing, but pay attention to the bass solos. There the bass acts like the rest of the band is the floor. That is what Phil does constantly. So, if you know the song, know where it's going, and know your scales, you can make the rest of the music the floor for your bass lines. John Cage will demonstrate that time and place are part of the music, and you can experiment with time and place throughout the song to create a new piece every time. Some passages are almost integral to the song, but even then, Phil would experiment. So you may not hear the same intro to "Help On The Way" everytime, but you still know that is the song coming up, even without a note for note rendition. So, don't try to "be" Phil, or even copy very much, just try to think like him, using your own influences.
A word of caution...some people will like it, some will understand, some will appreciate even when you fail, but most will not. This is the approach I use, and it keeps the music fresh and unboxed for me. Good luck exploring "The Phil Zone"!!