Yea you don't need a full party, a fairly well equipped light party will do just fine. I'm in a treasure hunting LS as well, and everyone there seems to agree that the loot drops regardless of party size, what's increased is gil. Just in the maps I've done with the FC and LS, 4-5 people get about 1600 gil, 6 or more 5000 gil each. Just my experience.