Soldiers Cove is a little different. Oddly, the outer samphire/weed speed bank is not part of any listed nature reserve that I could find, possibly because it is regularly inundated by king tides.

The foreshore at Soldiers Cove is a listed reserve, and is grassed, with multiple entry points to the cove itself. The speed bank and adjacent wetland, does not seem to provide birdlife with a suitable haven, in part due to urbanisation, inundation, landbased predation and lack of physical protection from the elements, especially during storms. On either side of the speed bank there is access and indeed jetties/ moorings for power boats. As such there could be little argument raised for a negative impact when using the area for windsurfing. The last time I read my maritime rules for the area, (Please correct me if I am wrong) the speed limits applied to powered craft only and therefore do not apply to sail powered vessels. From the birdies/conservation perspective, Samphire Cove (fenced) directly opposite on the western foreshore is of far greater importance, and the Creery Lagoon/wetland (fenced) is the jewel in the crown.
While I agree perception is definitely a problem, I feel that sailing in Soldiers Cove is unlikely to raise the ire of any birdwatchers/conservationists. In the past, the only problem we have experienced is the Police being called because a resident thought we required assistance/rescue as a result of sitting in the water at the top of the cove, waiting for the wind to pick up.