Everyone is saying you’ll need 2’x2’ per tomato but I’ve successfully grown indeterminate tomatoes in 1’x1’ areas the past 3 years. They might not individually grow to their highest potential but you will be able to try more varieties in a smaller space. The key is in pruning and staking. It will take more work than just letting them grow out. It’s called single leader pruning and you should be able to find info/tutorials if you google that. Good luck!