Seed envelopes are usually pretty specific about optimal plant spacing. Corn is highly dependent on wind fertilization, and wind full of pollen. A few stalks won't get you anything.

I've always enjoyed growing cowpeas. Recently I've added pigeon peas.

Where are you located? What size are the 3 beds you show and what is their orientation? I'm assuming that they run N-S and that the trellis is on the N end.

Regarding overcrowding, I grow bush zucchini (like Black Beauty), rather than the vining varieties. I also grow some determinate and semi-determinate tomatoes, which for me tend to be much smaller plants.

What Dan said, Read the seed package re spacing or google it. Corn won't be worth the trouble.

Each bed is 5x10 back is east. Bush zucchini sounds interesting. What tomato brands?

Rotate your crops. Crop spacing depends on the plant. You can put eggplant and peppers much closer together than zucchini or tomatoes.

I agree on the determinate tomatoes, they take far less room. I've had good luck with Rutgers here and a neighbor swears by Celebrity. I've grown Black Sea Man and it had a nice flavor but didn't bear very well early enough to be successful here.

I also grow the bush Black Beauty zucchini and a bush Delicata but they still take a lot of room.

Annie