As soon as the current txs are confirmed (1), I need a provably fair 0-9 RNG.
Okay so tell the user the hash of the seed that you do know, ask them for a random seed they provide themselves (for example, the transaction number of the transaction in which they sent you some bitcoins), wait for the block to confirm, then whether they win or not tell them the actual seed you used, the one you previously told them the hash of.
Notice that even if they lose, they still need to know what seed you had chosen, the one you had told them the hash of, if they want proof of fairness.
If you don't want to publish the proof (the seed you chose) on a diceroll by diceroll basis you can use aggregates such as having each day's seeds-to-use already in files ready to use (more than enough for each day, way more in case you get unexpected amount of traffic) and after the day is over move that day's file to a place where the public can see it, and publish there too the bet by bet / diceroll by diceroll log of all the dicerolls so the public can match up first roll of the day to first seed you had scheduled for use that day, second roll to second seed etc.
Log to public could maybe publish live realtime what the hash of your seed is, what seed a user provided, and, when the block is confirmed, what the dice actually came up as. Then once the day is over, publish the actual file of seeds and enhance the day's log by appending each seed that was actually used to the log entry of the play it was used by.
If you want to spam losing bets to the blockchain you could encode the seed you used into the "you lost" spam as well as coding it into the "you won" payments so the player can see it is fair as soon as they know whether they won or lost.
-MarkM-