Most of the time it's impossible because even if we can connect from the head node to the compute nodes, we cannot open an X tunnel there. So at the moment what

Most of the time it's impossible because even if we can connect from the head node to the compute nodes, we cannot open an X tunnel there. So at the moment what I do is copy the latest file to a filesystem on the head node and then run a lightweight X visualiser on the head node (Rasmol or equivalent is fine there). We have fancy complicated visualisers and they are great, but I really hope the (often old) barebone ones that work over an SSH tunnel on a flaky VPN keep working for a very long time.