This is very interesting to me (Zone 9 Southern California) as it is similar to how my gardening plan has evolved.

Several of my spring-planted tomatoes are still going (Early Girl and Sweet 100), though production has greatly slowed since it's been dipping below 50 at night. The quality is definitely less than at their peak but still clearly better than supermarket. I did not get it together to do a fall tomato planting this year, but over the past few months I've collected seed for several cold-tolerant tomato types such as Bloody Butcher, Ildi, Lahman Pink, and Black Prince. So next fall I will try plantings of those in Sept/Oct.

My tomatoes definitely took a production break in August during the hottest part of the year, but they did start up again as soon as the heat lessened. Peppers, eggplants, most everything else survived pretty well with constant watering. My peppers and some eggplant are still going. So I think vegetable gardening is possible nearly year-round. Per my "52 Weeks in the California Garden" book, I will be setting out new tomatoes (early types) as early as February. We'll see what happens.

My tomatoes took a break in August too, but we've been harvesting Matt's Wild Cherry for over a month, and the Romas that also sulked in late summer are producing a few, with lots more in the small green stage. I should have cut them back severely

The advantage of keeping a mature, heavily pruned indeterminate plant is that its root structure can support a faster re-start when the weather cools off.

I've got Early Girls that are turning yellow (not nearly as tall as Tracy's, but they get way more sun)

And ... if you like Eggplant or Okra, they LOVE the summer. I cut back the okra a week ago, experimenting with getting it to overwinter.

My peppers and eggplant are still going too. In fact, I need to pick an eggplant tomorrow and we're getting more peppers now than ever.
I'm planting okra next year ( husband will learn to like, lol ) and more eggplant.
Today my tomato seeds germinated. 5 days from planting!

I've been wondering whether to pick all the green Moretons, Black Krims and Brandy Boys in the garden at the moment. It's going to get pretty cold here tonight, although the tomatoes and the plants seem to be doing fine. I agree with tracydr about short season varieties being best for our climate; unfortunately so often they are very lacking in flavor. This summer I will cut back--WAY back--the big indeterminates and keep them alive through the horrid heat. lazygardens is right--at least the well developed root structure will already be in place. It was so hot I couldn't get new seedlings hardened off this year until late September or early October--way too late. Good luck with the winter crop. I'm not pulling anything, but I'm not mollycoddling anything either. I'm planning to set out my spring seedlings on or about February 1.

"I've been wondering whether to pick all the green Moretons, Black Krims and Brandy Boys "

then
"I'm not pulling anything"

I picked two beautiful ripe tomatoes today from the Patio. More coming!! Of course, it's a determinate so only so many tomatoes on the little guy.
Early girl is blooming like crazy despite her shady location an she's 40" tall, starting at 6" just over a month ago!!