Run standalone python script against mxd, not outputting layer file/package

The bulk of the code used in my script for reading this is from @RHB located here. His block of code runs fine with a current map open. Need it to open without an ArcMap session open. I tried as suggested shifting the parameters instead of “CURRENT” using a filepath for the mxd, at which point it fails to output the layer/file. Thought maybe I needed to add mxd.save() within the function in order to find the layer, but to no avail.

def load_feature_layer(fc_path, layer_name):
    # loads a feature layer into the active data frame in the current map
    # using a feature class path and a layer name string.
    # returns a layer object.
    mxd = arcpy.mapping.MapDocument("C:\temp\parser.mxd")
    df = arcpy.mapping.ListDataFrames(mxd, "*")[0]
    layerfile = os.path.join(arcpy.env.scratchFolder, layer_name + ".lyr")
    arcpy.MakeFeatureLayer_management(fc_path, layer_name)
    arcpy.SaveToLayerFile_management(layer_name, layerfile, "CURRENT")
    add_layer = arcpy.mapping.Layer(layerfile)
    arcpy.mapping.AddLayer(df, add_layer)
    arcpy.RefreshTOC()
    l = get_layer_by_name(layer_name)
    return l
    mxd.save()

def get_layer_by_name(name_string):
'''Finds a layer in the current MXD in active data frame by name.'''
    mxd = arcpy.mapping.MapDocument("C:\temp\parser.mxd")
    df = arcpy.mapping.ListDataFrames(mxd)[0]
    layer_list = arcpy.mapping.ListLayers(mxd, "*", df)
    desired_layer = None
    for l in layer_list:
        if l.name.lower() == name_string.lower():
            desired_layer = l
        if l.isGroupLayer:
            for sub_layer in l:
                if sub_layer.name.lower() == name_string.lower():
                    desired_layer = sub_layer
    return desired_layer    

if __name__ == "__main__":

    import arcpy, traceback, sys, os

try:

    outShp = arcpy.GetParameterAsText(0) # Shapefile
    outName = arcpy.GetParameterAsText(1) # String
    outLpk = arcpy.GetParameterAsText(2) # File .lpk
    #...<the beginning of your code>...

    layer1 = load_feature_layer(outShp, outName)
    layer1.description = outName

    arcpy.PackageLayer_management(layer1, outLpk, "PRESERVE", "CONVERT_ARCSDE", "", "ALL", "ALL", "ALL", "", "Footprint", "Bounding")

except:

    # PRINT ERROR MESSAGES
    tb = sys.exc_info()[2]
    tbinfo = traceback.format_tb(tb)[0]
    pymsg = tbinfo + "n" + str(sys.exc_type)+ ": " + str(sys.exc_value)
    arcpy.AddError("Python Messages: " + pymsg + " GP Messages: " + arcpy.GetMessages(2))

There are no errors when running it, it just fails to generate any output when pointing to the mxd.