But that's the point. What can they provide? It would be very difficult to convince HK Imd that they need to have meetings with a student! I'm sure they would also want proof of a company that she works for outside of HK as well.
Not trying to scupper you plans, but there are very few countries restricted to such limited visitor visa's. There have been many people who have met girls here with similar restrcited visitor status and have tried, unsuccessfully, to have their g/f's stay longer. The immigration department would pay more attention to a request like this.