I wrote similar code, but found weird behaviour when running JUnit tests 
on it.  I posted a question on the user forum, http://forum.hibernate.
org/viewtopic.php?t=945748.

Basically,backporting to your code:
 
Democrat proxy = session.load(Democrat.class, id);
Democrat visited = new PoliticianViewHelper(proxy).getDemocrat();
assertNotNull(visited); //ok
assertEquals(id, visited.id); //ok
assertSame(proxy, visited; //FAILS

It turns out that in the invocation of the accept() method, the 'this' 
pointer does not point to the proxy instance, but to a real instance of 
the Democrat class.

The Visitor pattern as you described is still very valuable, off course, 
but this one surprised me.