Looks pretty good. Can't all the post chunks be in the same tx though? Why create multiple txs when you can just create multiple OP_RETURN outputs? It's more efficient.
You can only have 1 OP_RETURN output per transaction.
Having a limit at all seems counterintuitive, now that projects are finding ways around it (inefficiently). I think BCH could enable multiple OP_RETURN outputs without a hard fork.