Good advice above. Based off Hyosung's Owners Manual, I personally would recommend following their oil viscosity/temperature chart depending on the cold start-up temperatures your wife expects to be riding in.
While 10W40 should provide adequate protection, I would use the thicker viscosity oils in your application such as an HDEO in a 15W40 (like Rotella, which indeed is rated JASO MA2), or a 20W50. Most motorcycle companies that manufacture air cooled engines generally recommend thicker viscosity oils like 15W50/20W50 since engine temperatures are significantly higher than their liquid cooled counterparts; which places additional strain on the oil as a medium to further reduce engine temperatures (more so than in liquid cooled engines), and to achieve this while simultaneously offering proper lubrication throughout the engine/gearbox. Many riders have had great success with 15W40 in their air cooled Harley's and similar twins and has been shown to have great shear stability both mechanically/chemically, while the 20W50 will offer greater oil film strength thus decreasing the chance of the oil film rupturing leading to greater wear via metal to metal contact. Furthermore, as shown in the manual a 15/20 grade oil will have proper flow/pumpability down to 9-14 degrees, which should be more than adequate for your wife's riding conditions.
So...what oil? 20W-50 V-twin oil? 
