If you go to the second Turismo map in the fairground, zoom in on it and in the bottom right corner you see some graffiti. If you look at it, it seems to say Fort, then a garbled word under it. This garbled word could be the word Baxter if you squint, tilt your head, and poke your fingers in your eyes. It also has an arrow pointing away from it.
Just a guess, but do you think R* thought about having a fort there instead of leaving it where it was. Perhaps the idea of using what was the 2nd island in VC as the first island in VCS did not occur to them for a while.
Just an idea.