If you want to be really keen then use one of these:
https://www.kryptonitelock.com/products/ProductDetail.aspx?cid=1001&scid=1001&pid=1123I used one of these before I got the SPT tie-downs. It just fit really snugly around the board I had at the time.
You could run the two SPT tie-downs through the ends of the cable then around something immovable.
The tie-downs don't stretch so you can't easily slide them off the board. The cable would stop you sliding them outwards away from each other.
The only thing you would have to worry about is a frustrated thief taking an axe to your board.