Their private mempool, I am assuming , is not shared with their own miners who only need to report back the nonce so they can mint the new block.

In the last week, their pool only found the nonce 61 times -- Your TX could easily take hours to get a confirmation.

While you wait, it would be wise to have your own bot looking out on the mempool for a spend from the puzzle addr you sovled.

I mean, it is very possible that someone just happens to also solve the puzzle at the same time, or a rogue miner got your pubkey from MARA's pool. (unlikely)

If your bot spots the pubkey, you are fucked, since you are now fighting against other bots pushing the fee higher and higher.

You could however be very lucky and the next block just happens to be solved by MARA and your slipstream TX is safely included in their block.

It is worth noting that I have no idea how the inner workings of miner pools like MARA work.

We have to patiently wait for someone to solve #67 and take the risk.