I don't see that a Dovado box in Bridge mode can solve the problem that the ISP assigns a non-route able private IP address to the WAN connection, thus the WAN connection at the remote site can't be accessed from the control site via the Internet.
The Dovado box in Bridge mode seems just to be a router with fail over between two Internet connections.
The Dovado box can do VPN, that is clients on the LAN at the remote site can access the Internet via VPN. In other words the VPN seems to be initiated from the remote site. The problem in this thread is that the control Remoterig box must be able to access the remote (radio) Remoterig box, that is the VPN should be initiated from the control site. If the Dovado box can initiate and keep a VPN open (to a proxy server) then it will work. I have not found this in the manual, is it there?
73, Palle, OZ1RH.