I think easiest would be to take 5 of the ints, and pack a gamertag of the person hosting in there, four latin characters to an int.
When matching, you can then have a function to "match any friend" or "match a selected friend." If your friends list is really long, that might take a while, as you'd have to try querying for each friend separately, unless you know there will be less than 25 sessions hosted, in which case you can query for all and do your own matching.
