Some advice mate...I use sketchup STRICTLY for accurate geometry in buildings mostly...when you export as a DXF or OBJ it will ask you how many triangles etc per face...I dont know if a zero input will give just the one face. Personally that shape would be easier to make in Maya mate...then use deformers to achieve what you want. I have exported from sketchup to Maya and it gives really crap geometry man....avoid it if you can.

cheers bullet