You can rebind dom0 copy/paste shortcuts to for example Super-c and Super-v in /etc/qubes/guid.conf. This decreases the number of keypresses by 33%.
For your specific method, you can probably figure out something with xsel, qvm-run-in-vm, and the dom0 clipboard file.
For example, copy might be implemented by triggering a keyboard shortcut that runs
qvm-run-in-vm -p $activevm xsel > /var/run/qubes/qubes-clipboard.bin
Here $activevm can be obtained from parsing the output of xprop -id $(xdotool getactivewindow) _QUBES_VMNAME.
It’s probably not worth the trouble, though.