I didn't have the space either. So I built Self Watering Containers for mine. I planted two in each 18 gallon bin and placed them in the rows between my beds. That way they could share the trellis. It is an easy and relatively cheap solution. I've got links on my blog if you're interested.

Good luck!

Here is a link that might be useful: Sinfonian's garden adventure

I would probably also use some type of container, and plant something else in your spots on the trellis, cucumbers maybe?

5 gallon pails work great for toms, as do 1 1/4 foot volume containers

Here's trudi's photo of her beach-pails in her driveway from the wintersown.org site:

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littleonefb's pic from a tomato thread on the Winter Sowing forum

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5 gal pails right-side up...

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And the (becoming very) popular upside-down 5 gal bucket method:

Seems to me you don't have quite the problem you believe you do, unless you have a different tomato than Fourth of July. You wrote that your tomatoes are determinate whereas Fourth of July tomatoes are indeterminate. The other suggestions on this thread are great for creating more room for other veggies, but you can still plant your tomatoes in your raised bed at 1 foot intervals and grow them as you originally planned.

Here is a link that might be useful: Here is one link. Google it if you don't trust Wiki