I know there's the script posted in the Tips and Tricks section, but I'm wondering if it's possible to install the system partitions (root, home and swap) on the encrypted LVM. The graphical installer doesn't have that option. And the script that was posted seems to not be able to install to existing LVM partitions, only regular ones.

Any advice?

P.S. Sorry if the post is short, I'm doing it from my phone.

As you noted, this feature does not exist in our installer. Nor do we allow installs to RAID. Adding this feature would not be too difficult but there has not been a lot of demand for it and our developer resources are not infinite. If you have a spare partition or even a spare usb storage device then you could do the install to that and then copy the installed system to your LVM partition. You would have to run grub-install manually and you may need to update the initrd/initramfs to mount your root partition. You would also need to have a separate /boot partition so the bootloader, the initrd/initramfs, and the kernel can get loaded before your LVM is mounted.