Think of placing two fence posts opposite each other around the plant. Then tie string, up and down, to the two posts. Use as much string as you need to loosely cage the plant. You won't be containing as much as encouraging it to go up. When you see a new branch starting out and down, justly gently pull it back in behind some string and point it upward. It is probably easier to redirect than to contain.

My plants grow vigorously in my zone, but I don't prune because I want to encourage all the blooms I can. The sun shines really hot in my zone so I keep all the leaves to protect the fruit from sunburn.

you should still be able to reach the tomatoes. Just lean in and get them.

"Should we just trim off any part of it beyond the size we want it to be?"

If you don't want the tomatoes you will never get by doing that. It is your plant and you can do as you wish.

But most of us grow for the tomatoes so we let the plant grow naturally. Or if we have limited space we pick a variety that stays relatively small. Do you have any idea what variety of transplant you bought?

As the others have said it needs to be properly staked now, and with big stakes as it is far too late to cage it now.

Here is a picture of what we are talking about.

Then you just run the strings around from stake to stake to support it. Reaching in to pick is not a problem/

Dave

I don't think you will lose much productivity from that pepper plant by just leaving it where it is. Plus that pepper plant is a slow grower. You can just coax the tomato vines away. You can tie the tomamto vines up. It want hurt the pepper plant if the tomato grows close.

Are you sure that is just one tomato plant?

That fence behind it could be pretty handy. I'd run some lines from stakes in the ground (maybe under those bricks on the border) up to the top of the fence (maybe loop around a fence board at the top to avoid having to set some screws), and start tying up the plant to those lines. You could even add a few cross lines, and end up with a really coarse net.

Now, I'm assuming those aren't cherries. If they were, they'd be over the fence and draping down the other side in no time.

I'm also a little surprised that's just one plant.

In my opinion there is some optimum level in production and foliage size.

Even if you decide to keep all the lateral branches, least you can do is to lighten up some of the leaf branches, to help air flow through the plant. This make more sense about trimming the lower leaf branches within a foot or so from the ground , also, the yellowing leaf branches. They make no contribution but may invite some disease. JMO

Sey

Why would you want to make it grow vertical? Let it sprawl and it will grow way faster.

sey is exactly right...you need to "air out" that plant before you have a diseased mess. Rather than chase your tail all summer...provide more than adequate stakes and supports...and let your plant catch up with the support system.

I would move the pepper. It is already getting pushed aside by the tomato.

"Why would you want to make it grow vertical? Let it sprawl and it will grow way faster."

As the OP said, and as you can see in the pics, it is overtaking the nearby desirable plants. There isn't room to allow it to sprawl.

Rodney