Time for Beach after Carnival Stingray Excursion

[luvtovaca]

Both of the Carnival sponsored stingray/reef excursions we are considering are 3 hrs. (approx. 9 am-12 pm). If we are docked 8 am -3 pm that day, would we have time after the stingrays to stop somewhere on Seven Mile Beach for a short visit (maybe Reef Grill or Sea Grape?) Assuming the excursion drops us back off at the pier, we'd have to take a cab to the beach. Is this too tight for time? We decided to stick with the Carnival sponsored excursion for this port only as we are concerned with time for tenders, etc. and don't want to spend the day worrying about missing the boat!