You don't need massive machines, you need a certain ratio of crops to labour and capital.
If the go kart tractor allows experimentation with automation and presently difficult to automate farming methods or crops then it may be viable.
It won't compete with the ten hectares of wheat needed for one person to earn a living wage even without other costs, but there might be a niche for produce rather than calorie crops that looks like 1000 gardens rather than a vast ocean of corn.
Edit: Opened your link to the rather small tractors, this is what I had in mind with the one in the article being more along the lines of what the reprap was in the 2000s compared to a ratrig now.
If the go kart tractor allows experimentation with automation and presently difficult to automate farming methods or crops then it may be viable.
It won't compete with the ten hectares of wheat needed for one person to earn a living wage even without other costs, but there might be a niche for produce rather than calorie crops that looks like 1000 gardens rather than a vast ocean of corn.
Edit: Opened your link to the rather small tractors, this is what I had in mind with the one in the article being more along the lines of what the reprap was in the 2000s compared to a ratrig now.