I think 3DXRing is on to something. I know it would be additional effort on the administrative side but flighting sounds like an answer. KEEP all equipment rules & entry fees in tact. I would suggest 3 flights, Championship, 1st & 2nd flight. Flights 1&2; $100 gift certs to the top 5 in each. Remaining monies could be split between evenly among top 15 in the Championship flight. Plus the top championship flight shooter would be crowned "World Champion"