depends on how mobile you want to be with the kayaks
Flinders "most" times will be ok straight off the beach for kayaking
or take the kayaks to brown lake, not a bad way to finish off the camping trip anyway, get to clean up the kayaks in fresh water
good kayaking in the Bay (Dunwich to Amity)

the rest of the advice is spot on, not far up the beach to Adder rock to get water