So I have looked far and wide (but maybe not enough) for the answer. Historically, you could avoid the LiveCD and use the alternateCD / text installer to configure software RAID 1 on two internal disks at the start of install. Apparently this is still working for Ubuntu 20.04 SERVER edition. But I cannot find a solution for the DESKTOP edition as it only seems to come via a LiveCD now. I need displays and TK as the application I am testing in different environments needs that. Am I missing something obvious? Is there a slew of packages I could install to turn a server edition into the desktop?
The computer system has two independent disks and no hardware raid -- either in a controller or in the BIOS. So it has to be setup in software. While I can configure each disk with the partitions expected, I cannot tie them together into a logical RAID volume to present to the Live CD installer. I could do this in earlier editions using the AlternateCD installer. Best I can tell anything but the Live Installer has been deprecated with no intent to support the Alternate in the Desktop release. Ideas? Thanks in advance.