I have a fairly large data model that I want to expose using Web API OData using the OData V4 protocol.
The underlying data is stored in a SQL Server 2012 database.
Looks like a mapping DateTimeOffset <-> DateTime will be included in Microsoft ASP.NET Web API 2.2 for OData v4.0 5.4.0:
https://github.com/OData/WebApi/commit/2717aec772fa2f69a2011e841ffdd385823ae822