Ed517 said..
I'm 64kg on a good day, and 1.81m tall, I'm finding the 131 fine, I don't have a big frame of reference yet though as I'm just starting out.
What would be a recommended length/width for someone who wants to go upwind, but wants to be able to get some decent air as well?
64!!! How about a KFC lunch tray

Seriously though - try all the boards you can get your hands on. Notice how the outline, rocker, tips width, stiffness etc all affect the handling... go from there.
Start around 140x42... being a lighter rider, you might find a smaller step is effective enough...?
(Epic Oxygen might be interesting for you..."