UPDATE: Using Christopher's advice as a guide, I went with eight bars starting in G, then sliding the G shape down the fretboard for six measures, building the discord and intensity, and then a break and back to regular old G.

This works exactly as I needed it to. I expect we'll add something more complex in the formal recording, along the lines of the underlying harmony and a sitar or such, as you suggested, but this simplified approach has the extreme benefit of requiring only an acoustic guitar to create, so that I can replicate it playing live at a writer's guitar with just my guitar.

Also it's super fun for this country/folk girl to play. :-) Makin' noise... I feel like JD when he covered Chuck Berry (see how I worked JD in there...)

Thank you again, Christopher -- I wouldn't have thought of simply sliding a chord shape down the fretboard without your help!