Labradors2: Thanks for the suggestion. I should explore other pollinators as well, and look into cultivating more bumblebees. I'd cultivate other kinds of bees if I could find any that really like tomatoes.
I have sweat bees that live in holes in a falling-down building near the farm. I watched the tomato flowers a lot this summer. I didn't see sweat bees on a tomato plant. They sure love the sunflowers.