Just for anyone who is interested we created a KA group for our Bayside Sailboard club competition . All sailors have to sail same local area on the same day. You can pick the day that you want and only tracks from that day will count. You can also pick locations yourself from a pick list.
We decided to do a 500m speed instead of NM as it is the world standard . The 500 m track appears on goggle maps for only those sailors in the group. Also got rid of 2 sec to stop the accuracy debate however you can configure your own menu if you want to include.
Did not include distance as this favours those with all day available which is not the case for most people these days.