In <5.5m wind you're probably going to want to jump, so I think the Kode 80 would probably be better than an iSonic 86 in that respect. Also, the inboard straps will probably afford you more control. For you, this board will be a full on sinker, so it'll definitely be reserved for high winds.
That's the one I would choose, maybe the SB team would recommend something different.
JP Super-X 106l, North F8 Ram: 5.8m,