Bro, try mo kaya kontakin ang EpicGames. I think they'd be willing to host (create custom room) your tourney for free. As for the mechanics, simple lang who ever survives wins.
Samin naman, nagplano ako for this year RoS tourney, 11 units lang dito so 1 for host and the rest participants. Kinailangan talaga gawan ng mechanism how everyone can join with enough thrill. Pag fireteam - 2 groups lang kaya; squad - you know how it'd look; solo - magbobosohan; so Dou Tournament ang i-host ko based na rin sa structure/alignments ng PCs dito.
Kunti ang PCs pero maraming players, kaya ginawan ko ng group stage. Maghapon ata booking nito haha. See attached: (as for the rewards, depende sa purpose, sakin it's for the fun, so yung reward > their cost)