Hi ManBird, welcome to the Forum!
I just saw your post, hence my late reply
That area of East Coast Park not covered by the 5km restriction (due to proximity to Changi) is "possibly" a fly zone, unless there are NPark signs indicating it as a NFZ.
Best bet would be to launch from the beach and fly over the sea, rather than inland, and stay below 60m. Hope this helps.
Cheers