Sorry. I think you'd need to have a whole cucumber patch around your tomato plant to keep raccoons away. Supposedly they don't like stepping on the vines. How are you going to get through them to care for your tomato?

Raccoons are omnivores but they prefer protein to vegetables. Are you sure they are eating your tomatoes?. I have heard the idea that cucumbers will repel them, but I have never heard someone say it worked for them. On top of that, a single tomato plant needs at least 10-20 gallons to thrive and cucumbers need almost as much. Growing together they would be much more vulnerable to fungal diseases and pests.

Here is a link that might be useful: Here are some other ideas for keeping raccoons away.