What Is The Best Tomato Spacing?

In this new place that I have moved to I’ve got this long, grey concrete wall, which by the way is awesome, because it’s going to fence off against the wind and provide support for tomatoes and cucumbers. The wall is almost entirely facing south, but 30 deg. towards east:

I’m even tempted to try and grow melons, because this is such a great spot, but I think that would be pushing my luck on this latitude.

The wall is more than 10 m (33 feet) long and I want to squeeze in as many tomato and cucumber plants as possible. I did a bit of searching and found 60 cm (24 inches) to be a good choice, and a popular one. And that’s about the tomato spacing I used in my self-watering tomato boxes earlier on.

10 m divided by 0.60 m = … a chest freezer? (17 plants). Nice.