You do not need a routable/public IP address, or a fixed IP of any kind. As long as it is the RV50, or a device behind it, which initiates the communication then remote access is perfectly possible without any dynamic IP services (which won’t get you through the NAT anyway) or special subscriptions, and will continue to work while roaming or switching operators. See here for an example of how to set up a reverse SSH tunnel, precisely to overcome this mobile network limitation: blog.hsp.dk/using-reverse-ssh-t … trictions/
And by the way, not providing public/routable IPs is not at all a “stupid restriction” but a perfectly sensible policy by the network providers, for a number of reasons - not least of which is the desperate lack of address space in IPv4. It only becomes an issue in remote M2M/telemetry type scenarios, when you want to put some kind of server on a NATed IP. Fortunately, there are well established methods for dealing with this situation: VPNs and reverse SSH tunnels.