I've been to Galveston a couple of times, but always stayed in the hotels. This year I'l looking at camping on the beach if possible. Would anyone know if there are campsites in Galveston, or should I just plan to go on down to Port A.

My days will be on the boat, so all I need for evenings is a place to shower, and sleep

Galveston State Park, San Luis Pass Die should have some camp sites too.