Export SVG without dialog box

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)