Re: How do we calculate the correct transaction fee to send?
in practice, miners would ignore such transactions unless they paid ridiculously high fees. so it doesn't happen.
such transaction won't even be relayed as it would be non-standard so it doesn't exist in 99.9% of the node's mempool. the only way to see something like this is for a miner to both create this transaction and mine it in which case there is no need to pay any fees.point taken, it wouldn't normally be relayed by nodes. however, that just means the spender needs to send the transaction to miners out-of-band.
