Another thought!
Have you ever tried a 8 string? A 8 string through a Big Muff [of any kind] is my favorite Drone setup, I tune mine to AEAD, and have flats for the bass strings and rounds for the octaves so it sounds like a bass and a guitar at the same time. And with some good muting technique, you can mute either the bass or octave strings so you can play lines in one octave or the other.
Have you ever tried a 8 string? A 8 string through a Big Muff [of any kind] is my favorite Drone setup, I tune mine to AEAD, and have flats for the bass strings and rounds for the octaves so it sounds like a bass and a guitar at the same time. And with some good muting technique, you can mute either the bass or octave strings so you can play lines in one octave or the other.