It is doable, could be a long day - probably 7-8 hours road time plus time for stops depending on your turnaround point from the east on I-75. It's a tool road, think the toll is $2.50 or $2.
Another alternative - if you want to see "older less traveled Florida" is to take Hwy. 951 south off I-75 to Hwy. 41 east & go to Everglades City. Can continue east on 41 past that, road is non interstate, much less traffic than I-75. Travel time is about the same.
I-75 south of Bradenton can be very busy all the way to Naples. There are some inland north/south non interstate routes but would add too much time to make trip as doable.
Anybody from the south Florida area can give you more details on stuff to do. Have not been in that area for a few years, the Hwy. 41 route is more scenic but the road surface may not be the best for a bike.