Since "Call Web Service Smart Service" is unable to specify endpoints

Since "Call Web Service Smart Service" is unable to specify endpoints that are not in the WSDL, I am using the "Send HTTP Request" smart service to send a SOAP request.
I have the SOAP request as a Document in Appian and use "Text Doc from Template" smart service to change the fields in the request (it is a simple request).
I was wondering, once I have the Document output, how can I retrieve the text (xml) from the document to send in the body of the "Send HTTP Request" smart service. So far I see no way of grabbing document's contents... thanks...

OriginalPostID-123078

OriginalPostID-123078