Honestly I think you'll love the 5'6" Potatonator. I'm around 74kgs and the 5'4" works fantastic in similar conditions. It's a slightly more traditional shape than the Sweet Potatoa with a narrower outline. The board plains immediately and is fast. Tail rocker is minimal but more importantly is the entry rocker which helps it to plain so easily. The double concave also helps. It will go with next to no kite input.

-Brian