Take three on reply... forum playing silly buggers:Starboard Hypersonic is not a good choice for learning planing, harness, straps, gybing, tacking etc etc (every other board would be better). I had a Hyper a few years back, technically difficult to sail... Takes a while to get the techniqure sussed, even as an experienced sailor.
Any larger freeride board would be a far superior and more enjoyable option (assuming you want her to become a wind addict). Don't think you'll find one less than 7kg though. Probably 7-9 kg.
I know this post is here twice, but if I delete one, both disappear