A companion would be best, but i have boys that fight with any other boy pig. I'm worried about getting them neutered when they are older as my 2 oldest boys were neutered (by a guinea pig specialist vet) and they now have huge hernias! (my other boys that were young when done are fine). I have a special hutch that separates 2 with mesh so they can't fight but have company (although i'm not too sure they appreciate it!!!!
I'd try a young boar, then if not get him neutered and get him some girl friends!!
And my vet charges £30 for a mate gp castrate, which is very reasonable, so i will be getting my boys done as soon as i can.
xxx