Make a single "Hybrid MBR" Image Instead of Separate BIOS/UEFI
gptfdisk
would be the tool to do this.
In-depth analysis of the pros/cons -- https://www.rodsbooks.com/gdisk/hybrid.html
The issue that either MBR or GPT misses out on any partition changes is mostly moot in a cloud environment. It would be extremely rare if an instance is booted with one, and then switched to another later in its lifetime.
While this is an opportunity to also address the ongoing #90 saga, if that turns out to be a bottomless rabbit hole, using grub2
for UEFI would be good enough in the interim.