Touchkit DatePicker - time zone client-server

Did anyone solve problem with dates in DatePicker, when server and client time zone are different from each other?

DatePicker uses String to send data between server and client, which eliminates time zone information.

In our current enviroment, server is located in US (OpenShift, -6:00 GMT) and clients are connecting from Central Europe (+01:00 GMT).
Difference between user entered data and data stored in server is either 7, 6 or 9 hours (US and CE have different DST intervals).

Is there any best practice to synchronize date data on server side? Or do I have to extend DatePicker rpc/state to adjust data manually?