A while back when I first got my otg cable, I was able to view my usb drive in twrp. I never tried to actually set it as my backup location tho. I assume it might work. BTW, are you using the free version of Titanium and rom toolbox, or the pro versions?

I'm looking for an app or method to backup both my apps, and my app data. I have a nexus 5, so I don't have an sd card option to backup to. I do however has stickmount, so I could backup to a usb drive. Though, it would be nice if I had the option to backup to a folder on my google drive. I have tried various apps, and they all seem to only know how to backup just the app, and not its data. (meaning, I lose all my progress on any games I have.) I've heard Titanium backup is supposed to be able to backup both the apps, and their data, but when I tried it, it only backed up the apps, and then when I went to restore my backup, it just installed each app one by one, and without the app's data.

Does anyone know of a good free (or free with premium option) app that will actually backup my apps and their data? My phone is rooted, is there some folder that has all of my apps' data that I can just backup?