No, all Vita games have to run from ux0. They don't have proper access on other mount points, which results in either the game not being able to boot whatsoever, or not able to save, and things like that.
The only thing you can do with uma0 is keep it as storage for ROMs, and some homebrew, and use it with Adrenaline for PSP/PS1 ISOs, but not Vita backups.