In my opinion those kiteboards around 145cm can't be considered real light wind boards especially for such weight as yours. Of course comparing with 135cm there will be some difference but still advantage will be quite little. I self use Aboards Glider 154 and very happy with it. This board allows me to kite even in very light wind and it's still possible to get sum fun out of it.
In fact, the length have little to do with your LW performance. It is the width that is VERY important. Thus a small board like the Epic Oxygen at 135cm only is still very performant in LW because of it's 47cm width. I am near 200lbs and use this one for LW kiting and I am quite often the fist in, last out with my Flysurfer 21m. Next summer I will use the Shinn King George which is 146X50 to get some extra low end. I live in a place with lots of LW days and I have tried a lot of LW specific boards, the width is the main things but there is also the gliding performance of a board and the rocker of course. You would be surprise if you could try a "small" Oxygen board
If my memory is good! a board that you add 1cm in length you will give you 3% more surface while a 1cm increase in width will give you 10% increase in surface! Here is a quote from Shinnusa website about that :
"Choosing your size
While many riders still look at just the length of the board when choosing their size, it's much more relevant to look at the width. The length of the board can be affected by the shaping of the tip and tail - which in reality plays little part in the performance of the board. For example: the difference in surface area between a 130 x 40 and a 130 x 42 is approximately 260 cm2. increasing the length of a 130 x 40 to 135 x 40 would give an increase in surface area of less than 200 cm2. That's nearly 25% less!"