Under 10 kts????? hmmmm that's pretty light wind, depending on your weight and the size/type of kite you use.
Actually a Spleene 164 Door is probably the best light wind board. This board allows you to get planing quickly and begin generating apparent wind almost instantly which enhances the performance of the kite. I'm 155# and I can go upwind in 8-9 kts with a 15m kite with this board.
not to change subjects but...
The kite is pretty important at this stage too. Most kites larger than 16m tend to fly too slow and too far off the edge of the window to be effective upwind machines. Although 17-20m kites can work prety well for heavier riders, aerodynamic drag is much higher on the bigger kites and this limits light wind performance going upwind.
The big foils are pretty cool for super light wind, but I'm a LEI rider and can only comment about foils from what I've seen and heard.