Companion planting in containers?

Note; containers are 50cmx50x50cm roughly.

I've just planted out seedlings of tomatoes and chillis, alternating per container. Question is has anyone had luck companion planting amongst containers like this. I'm thinking carrots, marigolds, dill, basil, possibly lettuce etc spread throughout. I don't want to end up with 16 basil plants is my worry. I'm not too phased about nutrients throughout the containers as ill be fertilizing etc frequently, unless anyone's had problems in doing this.