We'll be there in a couple weeks, and plan on stopping by Showcase of Citrus again. I need more Orange Blossom Honey, and theirs is great!
It may be a bit out of the way considering your route, but it is a good pick-your-own or pick-from-what-they-picked orange grove. Be sure you check out the website that Pineapple Whip provided in the pp, you can see which of their multiple varieties will be in season when you are there. Plus, you can sample any of the fruits they have before you decide which to buy!
We have also stopped at a roadside truck sale, and liked the fruit we got there too. It was nearer the E coast, on the way to the Indian River. Sorry I can't offer better details on that one.
Have a great trip!