Is there a way to trap the outgoing message that is sent via the pub.client.SoapRPC command?
Unlike with the document literal variant, where we have to build up the Soap message, I can’t get the actual string that is sent when using Soap RPC.
Any ideas?
I haven’t tried this recently, but you should be able to add the following configuration paramenter to your IS using the Settings → Extended menu:
watt.server.SOAP.debug=true
Let us know if this works for soap-rpc,
You did read all the posts here on why not to use SOAP-RPC, right? 
Mark