First, note that running Fiddler in a service account isn't a supported scenario; for unattended tasks, you're better off building an application atop FiddlerCore.
Your question in general seems to have nothing to do with Fiddler and everything to do with Windows Service accounts; you may wish to ask it in a more suitable forum (e.g. ServerFault or StackOverflow)
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items