You can try to expand all row details of the visible rows and update the DetailsVisibility property during the RowLoaded event. I have attached a sample project which demonstrates the approach.
If you want to have your code-behind clean, the way to go is with an Attached behavior. Please check this MSDN article
where you can find more information about it. Also you can check this article
about event handling with attached behaviors. In this way you will have the code in one place only.
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.