It works out approximately 9.6 sq feet.
The biggest issue I have is that you want to get a lone pig. 7 years is a very long time to live alone. He may well be ‘okay’ on his own but piggies aren’t wired to live alone. They need the constant company of their own kind. I’m afraid no amount of time spent with him can replace that. You can never truly understand piggy language - only guess at what he’s trying to say or do from others’ experience. As for his being aggressive and not liking being around other piggies - how many did they try him with? Piggies aren’t (usually) aggressive. He probably just wants to be the dominant one, in which case he needs a submissive friend to live with. And piggies getting on well is down to matching characters, much like humans. Would you like to live alone with no other human around , and only surrounded by large creatures you can’t communicate with or understand? Because that’s what it would be like. Can you see what a lonely existence that would be?
You (probably) won’t like it but I’m afraid I’m with Swissgreys. I would strongly recommend that you re think taking on the lone piggy, or any piggy at this time. Even if you did and got him a (male) friend, it’s not enough space for two boars. Lack of space for boars can lead to fallouts. If you decided to neuter him and get him a girlfriend, would your dad be willing to pay the vet costs? And, You say when you move you’d have more space. when would that be? I think it’s better that you wait till you have more space and can also adopt from a rescue. The piggies are health checked and more importantly, they’re already paired off.
One important thing - is your dad aware of vet costs for piggies? That’s also something to consider seriously.