Is there any way to install individual airports around the world without the huge continental files..?

Too unprecise of a question; elaboration required.

I think what the OP maybe means, say install an European airport and you don't have Europe scenery installed, you may see that the airport runways are surrounded by water. So I believe it won't be a good idea. You should install the European scenery first.

What te said. You have to install the terrain, airport comes with no terrain data. All the aitports in xplane are included wether yiu install rpterrain or not. Just be surrounded by water.