Question: Appropriate micro-payment target for paying the platform for use of blockchain bandwith?

I am currently working on a little extension to my MattockFS forensic file-system that tries to improve the integrity guarantees provided through a privilege separated provenance log for opportunistic hashing results, by putting large sets of log lines (that link storage entities to their BLAKE2 hash) into a Merkle-tree object and posting the Merkle-tree root on a blockchain.

If I would apply this idea to the steem platform, then a forensic processing station would need to do one micropayment each hour, where the memo field would contain the Merkle-tree root, what in my case is a base64 encoded BLAKE2 hash.

Payments to self for these purposes are obviously a form of abuse, as these hashes being put on the blockchain offer nothing to the platform, while they are of great value to the forensic process, as they go a long way in making provenance logs tamper-proof . But then, directing the micro payments to a random other account also isn't really the same as what would ideally be paying a small amount for the use of a small amount of blockchain bandwith.

My current design would try to pay the current equivalent of $0.05 USD in in either STEEM or SBD to an account representing the bandwith capacity of the blockchain. Problem is though, though I'm thinking witness, I'm not sure if there actually is such an account.

So my question:

Is there any micropayment target to what a micropayment would constitute a payment to the platform?

I could imagine cycling the top 24 witnesses might be the closest thing to paying the platform, as it is, as far as I understand, the witnesses task to provide the bandwidth. but then, maybe there are better options.