Can I turn off impersonation just in a couple instances

Make sure the Application Pool do have the proper rights that you need.

Then, when you want to revert to the application pool identity… run the following:

private WindowsImpersonationContext context = null;
public void RevertToAppPool()
{
    try
    {
        if (!WindowsIdentity.GetCurrent().IsSystem)
        {
            context = WindowsIdentity.Impersonate(System.IntPtr.Zero);
        }
    }
    catch { }
}
public void UndoImpersonation()
{
    try
    {
        if (context != null)
        {
            context.Undo();
        }
    }
    catch { }
}