Somewhere in the bay (roughly) near Coquina Key might work.
It's not far from the start- everyone will be running by the time they get there and hopefully nobody broke yet.

They will have to run a little closer to shore because of the point there.
Or... you could go down near the Sunshine Skyway. Should be a great day anywhere on the water!
Here's a view from the Skyway as a group approaches.