I found this Lubi installer (Linux Ubuntu Installer) which is similar to Wubi, except it allows to install any of Ubuntu derivatives and do it from Linux and not Windows. It is exactly what I needed, installing Ubuntu without having to burn to USB stick, mess again with the partitions, I have the iso downloaded already, it would be just install and run, really useful.
I've tried already to proceed as described here, however, even though all process was easy to follow and appeared to have been successfully executed, when I reboot PC, there isn't Ubuntu option to boot from in the Grub Menu.
Then I checked the requirements and it states that Lubi will not work on any systems using LVM, EVMS, or another logical volume manager, or filesystems other than ext2, ext3, reiserfs, vfat, ntfs, jfs, or xfs.
My home partition default filesystem is ext4, which is not listed in here. This may possibly be the reason why it doesn't work. Is there anyway to make Lubi work on ext4 filesystem? I've been on this thread already and some other people have this issue as well, but there is no activity in there for over an year and no further updates about this.