Add node annotations via agent options

Currently it is possible to add node labels etc via the agent options,

https://rancher.com/docs/rancher/v2.x/en/cluster-provisioning/rke-clusters/custom-nodes/agent-options/

We are looking at longhorn but to have ability to configure custom node disk setups requires passing in node annotations but it seems currently it is not possible with agent options.

Is there any hidden option to be able to pass in additional node annotations as an agent option, like we can with labels?

If not is it something expected in a future version?