Adding SOAP Header to SOAP call in PHP

Question

Using PHP 5.5.9, I'm trying to make a SOAP call and I cannot figure out how to add this header:

<SOAP-ENV:Header>
    <wsa:Action>https://websvcs.adtrack.com/SmartLeadImport/Submit_Lead</wsa:Action>
    <wsa:MessageID>urn:uuid:GUID</wsa:MessageID>
    <wsa:ReplyTo>
        <wsa:Address>http://schemas.xmlsoap.org/ws/2004/08/addressing/role/anonymous</wsa:Address>
    </wsa:ReplyTo>
    <wsa:To>http://stage.adtrack.com/SmartLeadImport/SmartLeadImport.asmx?wsdl</wsa:To>
    <wsse:Security SOAP-ENV:mustUnderstand="1">
        <wsu:Timestamp wsu:Id="Timestamp-GUID">
            <wsu:Created>2017-10-19T14:02:37Z</wsu:Created>
            <wsu:Expires>2017-10-19T14:07:37Z</wsu:Expires>
        </wsu:Timestamp>
        <wsse:UsernameToken xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" wsu:Id="SecurityToken-GUID">
            <wsse:Username>USERNAME</wsse:Username>
            <wsse:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">***************</wsse:Password>
            <wsse:Nonce>SOMENONSENSE</wsse:Nonce>
            <wsu:Created>2017-10-18T14:02:37Z</wsu:Created>
        </wsse:UsernameToken>
    </wsse:Security>
</SOAP-ENV:Header>

What I'm having a real problem with is the nested namespaces. I've tried a couple different approaches.

• Adding the XML to a SoapVar, then making that a header, but I can't figure out how to specify namespaces.
• Trying to create SoapHeaders, but those came out looking odd, and again, I don't know how to make sure all the namespaces get accounted for.

Any help with this would be amazing. Thanks.