Since you are using python, you should be able to do this using RhinoCommon
import Rhino
import scriptcontext as sc
import System.Drawing
import rhinoscriptsyntax as rs
dpi = 300
size = System.Drawing.Size(8.5*dpi,11*dpi)
settings = Rhino.Display.ViewCaptureSettings(sc.doc.Views.ActiveView, size, dpi)
svgxml = Rhino.Display.ViewCapture.CaptureToSvg(settings)
filename = rs.SaveFileName()
svgxml.Save(filename)