Hi,
I also do French Intensive /Biodynamic gardening, but am not anal about it (meaning= I do it when it has actual value/not just to do it), what I have discovered is that if you plant tomatoes that close, they will not thrive, you want every plant that you are, going to nurture and love on, to produce to it�s maximum ability, if you give your plants the necessary light,moisture,nutrients they will produce for you,God has engineered them to do just that. If any of these three elements are not present during the growing cycle ,they will not thrive, what you want is for your plants to compete with their "will to survive/propagate their species", they have an innate desire to make viable seed, ..........................they will produce seed,.......................... if you continue to extract their "offspring" before it is fertile, they will continue to create offspring that will allow their species to continue........in other words ....pick and pick often......never....... let a "fruit" remain on the vine ....on any plant......if the plant ever knows it has accomplished it�s one desire "to produce fertile seed", it will begin to die, it will not thrive anymore,,,,,,,it is your job to pick and pick often......never......let a plant know it has accomplished its desire.....never....never..............

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I plant them in 8� tall cages, each get four square feet of space, once they have grown over two feet tall, you may then grow other things in and all around them, just nothing as tall as them, they all want full sun.
You must build 8� tall cages, the cheapest /longest lasting is to use remesh, you can purchase that at most hardware stores, it is used in concrete like rebar, but it is wire with 6" holes, it comes in 5� tall and 8 � tall, go with the 8�, your plants with thrive. if you give them the opportunity to do so.

If .......you have full sun........I get 8 tomato plants in a 4� x 8� bed.....and after they are tall enough I plant beets, Kohlrabi, etc etc (big leaf plants) all around the bottoms.

1st year 700 lbs
2nd Year 5160 lbs
3rd year 9173 lbs
4th year 10799 lbs
Hopefully next year I can break the 12000 lb mark, I don't weigh what my family and friends eat, so I may have been close this year...