My friend who plays guitar has a band called illkillya and they didn't have a bassist. So what he did was modded his Epiphone Flying V with two output jacks and two volume controls. One output was for the guitar amp head (hughes and Kettner) and the other output went to a bass head. He played 13s on his guitar and strategically eq'd the setup to sound good.
I think this is a cleaver approach at improvising a 2 man gigging band. lol
Yes he played shows like this that turned out successful.
Just thought I'd share