在没有PHP库的情况下形成DFP广告管理系统肥皂请求

I'm stuck developing in an environment where I cannot use the PHP DFP library. I'm using PHP's SoapClient and I'm having trouble forming the headers correctly for SOAP requests. Here's the example:

<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope
        xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <soapenv:Header>
    <ns1:RequestHeader 
         soapenv:actor="http://schemas.xmlsoap.org/soap/actor/next"
         soapenv:mustUnderstand="0"
         xmlns:ns1="https://www.google.com/apis/ads/publisher/v201308">
      <ns1:authentication xsi:type="ns1:ClientLogin"  xmlns:xsd="http://www.w3.org/2001/XMLSchema">
         <ns1:token>SuchALongToken</ns1:token>
      </ns1:authentication>
      <ns1:networkCode>123456</ns1:networkCode>
      <ns1:applicationName>DfpApi-Java-2.1.0-dfp_test</ns1:applicationName>
    </ns1:RequestHeader>
  </soapenv:Header>
  <soapenv:Body>
    <getAdUnitsByStatement xmlns="https://www.google.com/apis/ads/publisher/v201308">
      <filterStatement>
        <query>WHERE parentId IS NULL LIMIT 500</query>
      </filterStatement>
    </getAdUnitsByStatement>
  </soapenv:Body>
</soapenv:Envelope>

It's the Authentication section that's getting me. Not sure how to set the internal params (type and xsd) and create the 'token' child.

    $header_params = new stdClass();
    $header_params->networkCode = self::$network_code;
    $header_params->applicationName = $app_name;
    $header_params->authentication = array('token' => $this->auth_token);
    $headers = new SoapHeader(self::getNamespace(), 'RequestHeader', $header_params);

This gets me the following:

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"  xmlns:ns1="https://www.google.com/apis/ads/publisher/v201308">
   <SOAP-ENV:Header>
      <ns1:RequestHeader>
         <ns1:networkCode>########</ns1:networkCode>
         <ns1:applicationName>Get Companies By Filter</ns1:applicationName>
         <ns1:authentication />
      </ns1:RequestHeader>
   </SOAP-ENV:Header>
   <SOAP-ENV:Body>
      <ns1:getCompaniesByStatement>
         <ns1:filterStatement />
      </ns1:getCompaniesByStatement>
   </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

Looks like wsdl is rejecting my authentication as well as my filterStatement. I'd be happy to get the authentication working at the moment. This request give me an 'Unmarshalling' error.

Any help would be much appreciated!