For my own sanity, I've started logging the troubleshooting I have done.
First, I ran an update. Then I decided maybe I wanted to do this in a tab to prevent these problems. So I added xiwi:
sudo sh ~/Downloads/crouton -t xiwi -u -n xenial
Something seemed to die when I did that process. My next step was to check the updated install.
This line is annoying, the first time I replaced "-chroot" with "xenial". That's wrong, actual use the term provided: "-chroot". That went wrong, too. However, this seemed to work:
sudo enter-chroot -n xenial
Next, I installed the crouton integration extension.
Now, we wait to see what happens.