Worth noting on this that while sync works, copy is the much safer option.
So
rclone copy source:/path dest:/path is what I'll likely end up using. In any case, the resulting solution still works.
Still need to tweak OSX a bit as it seems to kill the SSH session after some time for sporadic reasons - still testing but I may end up having to add ServerAliveInterval 120 to /etc/ssh/ssh_config to resolve that issue.