Hello Dave,
what you described is a widely used solution. It works well with the SunSDR rigs but you need a high speed network. Let's say 3 Mbit (or more) in upload.
In the picture below you can see how the bandwidth is related to the sampling rate you set on EESDR. It is for only one rx. When you add the second RX values just double.
There are different ways to develope a VPN. One is described on
my web page. It is free and it is based on opensource systems like OpenVPN and Raspberry PI3 but there are other solutions like make a subscription to a online VPN service. The last solution is not free but you have some time (usually the first month) to configure and test your network.
73' Enzo