Dog activities in (southwest) Florida?

My dog and myself are getting very bored with the dog parks / beaches
around here. My dog loves to roam open fields and forests, but the only
thing I can find around here are fenced in dog parks and very small dog
beaches that are way too crowded for our taste. In Virginia you could
always find a open filed, state park, etc. Does anyone one have any
suggestions for such places in the Tampa Bay area (Bradenton) or
beyond?

Thanks,

Mike