enableProxyMode for ipsecurity rule is no-go in IIS 7.5 (Windows 7)

The below configuration works in IIS8 (Windows 2012) and reportedly should work in IIS7+, however on my local Windows 7 machine this config causes WebServiceHandlerFactory-Integrated-4.0 to throw error 0x8007000d - Unrecognized attribute 'enableProxyMode'

If I remove that attribute, there is no complaint and ip security is working. But it seems this feature is a no go on windows 7/IIS7.5 despite what the docs say. Is this really the case?

<location path="MySecrets.asmx">
  <system.webServer>
    <security>
      <ipSecurity allowUnlisted="false" enableProxyMode="true">
        <add ipAddress="127.0.0.1" allowed="true" />
        etc...
      </ipSecurity>
    </security>
  </system.webServer>
</location>

The error message itself is obvious enough that this attribute is not supported, no matter what document says it might.

Meanwhile, the IIS.net doc simply means the section is supported by IIS 7+. It does not go to the level of attributes to describe which is supported by which version of IIS.