The squirrels are generally not in it for the tomato, what they really want is the water in the tomato. A lot of people (myself included) have eliminated or reduced the problem by having a birdbath or water display near the garden.
I actually have two, but the terms of their adoption require that the full extent of the victory be confined indoors. It's a sacrifice I'm willing to make for a kneading cat-doughnut on a cold day.