You probably have another router on your remote site, right ? From my point of view, you should be able to assign a public IP address into your hivemanager, pointing to the management interface of your AP. Some configuration need to be done on the router of your remote site (NAT). Moreover, you'll need as much public IP address as APs.
Aerohive could probably provide a better solution, or maybe you would have to use their "on cloud" solution.
What you want is to configure your existing Hivemanger as "private Cloud Service", so that any remote location can use it as Hivemanager via Internet. No VPN required. The configuration for this is less on the Hivemanager itself, but on the Router / Firewall connecting you to the Internet (you need to enable port forwarding for certain ports).
Please see this thread for a detailed description:
In a nutshell (minimum):
- Configure the Router / Firewall at you main location to forward traffic to its public IP (or assign a dedicated one if available) for UDP 12222, TCP 443 and TCP 22
- At your remote location, if there is a Firewall, ensure that all Access Points can reach that public IP on the same ports
- Ensure that your APs are being redirected to exactly that public IP