I use OCP for permanent cities and build about 2.7 temporary cities for every permanent one. The permanent cities have all the infrastructure needed to reach as large as a 42 population. The temporary cities only build units so unless they are next to fresh water they only grow to size 6 but a size 12 city even in a totally corrupt area can generate 18 science beakers when you get to steam power if there are 6 grassland tiles around. Once the permanent cities are maxed out on population I start removing the citizens from the temporary cities and abandonding them. This frees up the city center tile to be used by the permanent city to generate another happy citizen for 2 more score points. Coast tiles count for domination limit but sea tiles don't. Every happy citizen in your cities counts for score no matter where they are working.