I think the key is wait and see. I have a boar trio and it has been rocky at times. Sometimes there is grunting in the cage, never too serious though. when they hit the hormones you'll know who is the one causing problems and maybe plan another living arrangement. However, when they work, boar trios are awesome to watch! I love when they play all together, pop corning and chasing each other in the cage!
You need a big space though, so make sure they have room.