That is a long gap in rain! If you get enough sun, a solar still of the ocean water might work. They use salt here to chlorinate swimming pools, by applying power and breaking down the salt. They recover the sodium, and resell it (I think), and run the chlorine into the pool. I think, if you out gas the chlorine up on the hill top, you could get fresh water from sea water the same way. Solar panels might provide you with the power. I have seen some good ways of using waves and tides to make power. On top of a hill, you might look at wind power too.

I bet those fish are good, I hear that Red Fish are yummy! We have Bass (Stripers, Sand, Large mouths, and Small mouths) in the lake along with catfish and padlefish; so it can be fun here too! Once there, I plan to raise Tilapia in an aquaponics system. They should be easy to catch, LOL!