Too much work.You don't need a VPN server then. You want the client. You can also do that with an edgerouter X and send the traffic from only one device (or multiple devices) over the VPN connection. There's no easy toggle switch for it though. It would require you to login via SSH and issue a command. I haven't looked into it much more than that, as that's always been as far as I needed to go. But, I'm sure there are other things that could make toggling it easier.
That's why I'm thinking the Asus routers are my best option. Not sure which one.