Google Web Toolkit (GWT) + Google App Engine (GAE) + Detached Data Persistence

I would like to develop a web-app requiring data persistence using GWT and GAE. As I understand it, my only (or at least by far the most convenient) option for data persistence is GAE's Datastore, using JDO or JPA annotated objects. I would also like to be able to send my objects back and forth client-server using GWT Remote Procedure Calls (RPC), therefore my objects must be able to "detach". However, GWT RPC serialization cannot handle detached JDO/JPA objects and it doesn't appear as though it will in the near future. My question: what is the simplest and most direct solution to this? Being able to share the same objects client/server with server-side persistence would be extremely convenient. EDIT I should clarify that I still wish to use GWT RPC with GAE's Datastore. I am just looking for the best solution that would allow all these technologies to work together.