Yes stay away from Bunces pass! Rattle Fish is were I go for lunch or dinner on the boat all the time. In your 46 Cig from St. Pete you can get there in 20-30 min easy. Caladessi is very nice and a nice 30-40 min trip for you with great docks. This is a public island.
Also Sarasota is near too plus across Tampa Bay and up the Matatee River (well marked, very wide and deep) is a resturant with big floating docks called Mangroves with awesome food.
Someone mentioned Shell Island. It a nice place to beach the boat and hang out but it gets crowded with drunk people and with a boat as big as yours I would not tempt it. It is super shallow around there so you must know where you are going and be an expert at handling the boat in tight areas.