I've flown over this bridge a few times now, the lowest was at 1,500' just inside the Bravo.
Departing and landing at Peter O Knight inside the bay, if I'm taking people sight seeing I'll takeoff and head east away from traffic and away from the Bravo where I can get a feel for how my potentially first-time passengers are doing while listening to approach. Then I'll ask for the VFR corridor from east to west over Tampa Int'l until I hit the coast where I'll head south along the beaches and then up into the bay. If they need me lower than the 3k-ish I prefer, I just stick closer to the actual coast lines rather than in the middle of the bay.
Not only has Tampa never NOT given me clearance into the Bravo around there (sometimes it may take a minute so plan ahead/act accordingly), on one weekend they had control of the MacDill Class D and had me fly through there to approach Peter O for landing. That was a shock to me, but it was direct rather than skirting the bay along the shore at a lower altitude.
I caveat these thoughts with the fact that I'm flying my OWN plane and I know the maintenance history and I'm not in a rental wondering who or what flew it before me. Seeing how your rental seemed to not be in top shape, I'd ask for Bravo clearance at a high enough altitude that you're comfortable, but if Tampa is landing heading north and Sarasota has departures heading north/northeast then I could see Tampa not giving you what you want.