Can you launch the work as a “scheduled task” within Windows?   Or can you get and install a true batch-job monitor on that Windows box?   What this is going to come down to is, you need to tell Windows to run that program, as a particular user but not connected to a user session, so that the user can start the job and then disconnect, then log back on the next morning and check the job’s completion status.   “Citrix or not” would then drop right out of the picture:   you would now approach the task of “getting this work done” in the same way, whether you are physically sitting in front of the box or not.

If you are doing work that requires (up to) 8 hours to run, I think you need a batch job monitor regardless.