If you're dealing with a share that's used by multiple clients who can't/won't use other protocols, you can create this setup:
clients.lan | <--SMB through LAN--> | \\proxy.lan\share
proxy.lan/share | <--SSHFS through Internet--> | server.in.the.internet/share
In other words, on the remote server (
server.in.the.internet), enable SSH;
On a local server (in your network
proxy.lan), mount the remote folder through SSHFS
and share this folder on the local server via SMB.
That way, clients in the local network can access the Samba share on proxy.lan, yet it's transparently (for them) proxied from your remote server; you could even set up caching on the proxy so that the access is even faster.