I don't know why it took me a number of hours to find the fix for this but I found how to set the resolution on a blog called Random.GetNewEntry().
What is interesting about the fix is that it doesn't involve configuring X Windows. It is a simple change to the GRUB launch command.
I am keeping a copy of the changes needed here for my own reference, but 100 internets go to the owner of the blog.
- Edit the grub configuration file, for example:
sudo vi /etc/default/grub
- Find the line starting with GRUB_CMDLINE_LINUX_DEFAULT, and add "video=hyperv_fb:1680x1050" (or your custom resolution) in between the quotes. For example:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video=hyperv_fb:1680x1050"
- Save and exit
- Restart your computer