Of course another option for SOAPProxy... you could leave the existing "wsdl" property format as is and add support for a new (alternative) property that has exactly the same name and value format as the SOAPProcessor i.e. support 2 options.
URI:
<action ...>
<property name="wsdl" value="http://...."/>
... etc
</action>
and, endpoint ObjectName...
<action ... class="org.jboss....SOAPProxy">
<property name="jbossws-endpoint" value="foo:HelloWorldWS"/>
... etc
</action>
Raise an error if both are configured.
Just say'n.