I wouldn't discount the elemental diet so quickly. I know there is a strong opinion floating around that you can't starve away SIBO, but I just don't buy it (or, rather, I think this is a misinterpretation of the correct info that you cannot starve it via low FODMAP, BI-phasic, etc).
Both extended fasting and elemental have show significant results in peer reviewed study. Elemental actually has a higher clear rate than antibiotics and antimicrobials -- 80% or higher vs 70% for the latter treatments. The only reason it isn't a first-line treatment is because it is considered unpleasant and difficult for some people to follow. I personally can't fathom not being willing to endure some short-term discomfort to potentially get rid of this thing. This is life-long misery, at least when you have it bad enough. Do the damn thing. Save these far less studied options as a last-ditch effort, or better yet use them to heal things up AFTER you've cleared SIBO.