I think all Magic Gorter was saying was that the Lighthouse restriction was from an earlier incarnation of the rules for this game, and, when he changed the rules after closer inspection of the map, he forgot to remove it. We are following the rules laid out, which say no ships until size 20 and magnetism.
If you have inland cities, your ending will be delayed by the amount of time it takes to get ships to each landlocked city from the nearest port. If you think you can shave enough turns from getting to size 20 and researching magnetism by building inland, then you have a viable strategy by doing so. Another alternative is rushing to Radio and using airports. The absence of tech hiding means this is not completely ridiculous, and the delay in finishing if you have landlocked cities makes this a more appealing option (though I doubt that with only 4 cities and no trade, that enough science can be generated to get to radio quickly enough to make this a valid alternative).
Remember that you can work any ocean tile that is beside a land tile, so there are lots of coastal sites with only 1 or 2 covered squares, and some without any at all.
