In the Northeast, outdoor showers are commonplace in beach houses and summer homes, but not so much in Florida as far as I can see. The newly installed outdoor shower will be handy when coming off the water to quickly cool off or to freshen up.  

Captive Island offers more opportunities than Sanibel if you are looking to tie up for the day. During the off season Tween Waters Inn allows you to dock and use their facilities and beaches as if you were a paying guest. Great pool, bar and food service right to your lounge chair. The best part is the price, $35.00 for the day and get a $20 credit at the bar. There other bars and restaurants in the area that offer transient docking too.

Although St. James City doesn't really have any beaches to speak of, you can however take a 20 minute boat ride to Sanibel Island. The beaches of Sanibel are known for their white fine sand and emerald green water. As long as the winds are light you can round the lighthouse and throw the hook.

Here is a video I found on YouTube with Manatees frolicking in the same area as when we visit Sanibel Island.