Dave,
This exact pull request introduces notion of TZ and non-TZ classes in
jdbc driver: https://github.com/pgjdbc/pgjdbc/pull/340
Well, the PR needs some cleanup, however it allows to bind variables
and tell server we are binding TZ. I think it would solve the issue.
Another approach is to support java8's java.time APIs, however I think
it is more like a long-term solution.
Vladimir