M-sorry no one has posted a reply-i would use the seaweek- let us know how it works if you use it. Michael

I know that later when it comes time to set fruit I'll need a different formulation so that I'll get better fruit instead of foliage.

But for now - trying to revive these plants and get them to grow up nice and strong - what kind of fertilizer should I use?
Being poor and liking things to be as simple as possible, I have used only grass clippings, kitchen scraps, and crop residues for fertilizer for 34 years. You could just put a few inches of grass clippings on top of the soil around your tomatoes and they would feed your plants better than anything you could buy.(Make collars from yogurt cups to keep the clippings from touching the stems. That could rot them.)
The clippings have these advantages:
1. They are Free. You mentioned two things, fish emulsion and seaweed, that sure ain't cheap. Why spend money when a free material is not just as good, but better?
2. You talked about "formulation." If you used something like fish emulsion, with its high readily-available nitrogen, that could actually reduce the number of maters you get. If plants get too much nitrogen, it blocks the absorption of phosphorous, which is crucial to fruit set. This can never happen with grass clippings. Your plants will get the right amount of each nutrient, at the right time, in the right form.
3. Add to the above that the clippings will reduce watering and eliminate weeds, and this seems like a "no brainer" to me.

Oh, another thing is the exposure your maters are getting. Everyone knows when it gets too hot, plants stop bearing. The heat kills the pollen before it can fertilize the blossom.If your plants get all-day sun, shading just the pots from the afternoon sun can keep the plants enough cooler to get fruit in hot weather. If you do get little or no production during hot times of the year, you might also think about investing in a little shade cloth to keep the afternoon sun off the plants as well.