Following is a route that I would suggest. It’s a little confusing but it will get you to Starkey Park from the Pinellas Trail. Some local may have alternate suggestions. But do not go on Keystone – it is under construction and I don’t even like riding it in a car. Hope this helps. Good luck.
Alternate 19 (N. Pinellas Ave.), 19N, Mile Stretch Rd., Grand Ave., Perrine Ranch Rd , Seven Springs Blvd., Mitchell Ranch Rd., SR 54, Starkey Blvd to Starkey Park.
SR 54 has a bike lane and is fine to ride on.