I found a way to create a keyboard shortcut that takes a screenshot of my full desktop and automatically saves it to my personal qube.
I did this in two steps: First, I saved the command as a script, and then I created a keyboard shortcut that executes that script.
Step 1: Create script Create ~/screenshot-fullscreen.sh in dom0:
filename=~/Pictures/Screenshot_$(date +%Y-%m-%d_%H-%M-%S).png
xfce4-screenshooter --fullscreen --save "$filename"
qvm-move-to-vm personal "$filename"
chmod +x ~/screenshot-fullscreen.sh
Step 2: Assign keyboard shortcut In dom0's XFCE Keyboard settings, create a new shortcut that launches this file.
Bonus: I actually created three keyboard shortcuts for three different screenshot options:
Fullscreen: Keyboard shortcut: Super+Shift+3 Command: Launches the script above
Window:
Keyboard shortcut: Super+Shift+4
Command: Same script as above, except substituting --fullscreen with --window
Select region:
Keyboard shortcut: Super+Shift+5
Command: Same script as above, except substitute --fullscreen with --region
Other options could be different keyboard shorcuts that save to different qubes. Or using qvm-copy-to-vm instead of qvm-move-to-vm. The screenshot tool has more options like excluding the window border, etc, and those are listed by running screenshot-shooter --help in dom0.