I have a Starsufer for my kids and like it (30, 40 and 50 kg). At 30 kg, it will be quite stable for her, probably more than enough.
We use 2.0, 2.5 and 3.2 rigs with it. I'm sure it works fine with the 2.5, but I think it is also good with the 2.0. I put the mastfoot has much backward as possible.
On important trick for us is to use the smallest and cheapest fin I could find in the back instead of the much larger included plastic one. Use the second plastic fin in the center. This will bring the CLR forward and also allow for easier tacking. With the large plastic one in the back, my 40 kg girl cannot tack the board with a 2.5, but has no problem with the small fin in the back instead.