Back on older Halos you could change your Xbox language/location to some far away country and increase your chances of matching with the other party. It wasnt a sure thing, just bettered the odds. Not sure if it works on XB1, though.
Finally figured out how to boost and get matched with a full group. It takes a few tries but I've finally done it. If anyone wants to boost, I'd prefer you have a second Xbox one and copy of h5. Pm me.