I was prepared to make that same suggestion, Ron. That is until I visited the referenced site for GNU httptunnel. I can find no explicit statement that the HTTP tunnel will support UDP packets. In fact, looking through the archives of their mailing list, there is an unanswered question from over two years ago in which someone asks about UDP support.
In looking at other, similar solutions, I noted that one such product, HTTP-Tunnel, states that their particular implementation does not support UDP tunneling.
Adar, I would certainly encourage you to give it a try. In order to get the remote library to be visible, it will be necessary to tunnel the DAAP beacon, by proxy, to the local, client subnet. Should httptunnel prove to be a robust and versatile alternative for situations wherein more restrictive firewalls are utilized (i.e. where ssh tunnels are blocked), it would be a great piece of information for the FAQ and the project in general.
Please report back with your findings should you decide to try it.
Herman