You will really be OK to do it the last day... it's not like the normal tour that you do. Very relaxing, not hurried at all. And the zoo thing is not to be missed. Even that is kind of a stroll before you drive again. It's not a long stop at all (and we had rum punches with us...)
I think it would be a great way to wind down the vacation.
You will love it!! Can hardly wait to meet ya'll!