WSA can be running in a specific mode Connector Mode with CWS. In this mode, you will have granular options to send traffic to CWS.
For remote users, best way is to use AnyConnect to send the traffic to CWS. Alternatively you can enforce the browser's proxy settings to force all traffic to CWS. However you may need different approaches for different browsers.
You can use pac file to control the traffic sent to WSA or CWS for traveling users based on the source IP.