Depends on the footprint of the tank, if you get all females or males you have a better chance of keeping a few together but seeing most tanks in that range are onlly 30-36 in long i wouldnt do anything other than a breeding pair.
HRP's are generally, IME, less aggressive than cons. you could try 2 pair but keep a close eye and have a backup plan should too much aggression occur...and that'd only be if the tank is at least 3 feet long. if you want to be safe then just keep one pair with some platys or something.