You need to know if it is possible to use the Cloud Connector as a Proxy or VPN to tunnel the traffic from C4C to On-Premise network, on Outlook Server Side Integration.
SAP Cloud for Customer
This is currently not possible.
You can suggest this as a new Idea using the following:
1. If you are a partner: please use email@example.com or the Partnerfinder
2. If you are a customer:
a. Contact your the Account Executive
b. Check the link https://www.sap.com/uk/services/advisory-development/application-development.html#contact-us
C4C : An alternative option may be to check the SAP Cloud for Customer Ideas Forum to submit an idea: https://influence.sap.com/SAPCloudforCustomer
KBA , LOD-CRM-GW-SCC , Invisible CRM - Smart Cloud Connect Solution , Product Enhancement