What is the best way to share a template around multiple different engines?

I have multiple self-hosted engine clusters around the globe. These do not (and cannot) share any form of network storage like NFS. I create a 'golden image' template in one cluster, and want this template on all other clusters.

Currently my process is:

- export template as OVA

- scp template to a host in every cluster

- manually through the GUI upload the template OVA

It is this final step I am hoping to automate. I cannot find an obvious way to do it via the API - I can only import it as a VM (not a template) or upload a disk image.

Regards,

Jake