I see what you mean, taking on another animal is a big responsibility. However, if his cage is big enough for two then you're probably only looking at the expense of initially getting the new pig which would be a donation to a rescue probably? Veg wise my pairs of pigs get the same as what my solitary pig got more or less, same with hay and dry food should really be kept to a minimum anyway because you want to encourage them to eat more hay and veg. Only you know your situation though, if you can't afford another you don't have to get one, he's done ok alone so far x