Thanks for the tip, ravells.

I actually gave up doing the map on Illustrator (or Inkscape). I'll do it using an editor for OpenStreetMap (JOSM) since I managed to render it nicely. This way I'll have a navigable map and don't have to worry about labels.

My major struggling now is to make the road map plausible. It's hard to develop everything from the ground up and make it look like a real city (I don't know where to put the streets). My idea is to start with the main roads, but even those I'm not sure if they're in the right place.

Also, I have no sense of scale, so I'll need real world references to make it but still don't want to just copy it.