DeadlyFoez was the first to get it done. It's also been achieved on Dolphin Emulator!
Details:
Boot2 Wii used
Startup Menu WAD file installed via WiiMod Lite
Startup Menu running on cIOS60 (slot patched to IOS4 using ShowMiiWads).
The cIOS'4' has patches to allow running burnt DVDs on the Wiis drive
Startup Disc is the 'RAAE01-v0.prod.gcm' file.
Extracted and rebuilt to a normal Wii ISO using Wimm's WIT Tools (thank you IPG for the idea)
Burned to a blank Verbatim DVD-R disc using growisofs on Debian 10 (growisofs -dvd-compat -speed=8 -Z /dev/sr0=my.iso -quiet)