sudo using X11 forwarding

I have a need to export my display from a RHEL host AFTER I have sudo'd to root... (such as virt-manager console)

xauth list | grep `uname -n` > /tmp/`logname`-xauth && chmod 660 /tmp/`logname`-xauth
sudo su -
LOGNAME=`logname`
xauth add `tail -1 /tmp/${LOGNAME}-xauth`
virt-manager