Are you just looking for a partition editing tool? Rescuezilla ships with gparted and some other backup/rescue tools and boots from live usb though gnome disks isnt included if i remember. Gparted distributes its own live boot utility. You could also look into making a persistent live installation of ubuntu or other distro and have those installed and theyll remain on the disk.
Edit: Rescuezilla comes with gnome Disks so this may be what youre looking for