You can sell „private cloud” so you make separate server or servers for that specific customer. On premise goes away and you can also setup private cloud to be

You can sell „private cloud” so you make separate server or servers for that specific customer. On premise goes away and you can also setup private cloud to be filtered on firewall to give access to customer only or connect it via vpn or whatever else. Biggest upside is that you still control deployment and are responsible for uptime but you have best knowledge in-house to deal with it.