how to get SAML Response to backend application protected by SP

[Roman CHRENKO]

Hello.
I would like to ask if it is possible to send the whole <saml2:Response> from SP to the backend application. The same question was sent by James Paul at Tue Sep 15 13:47:08 EDT 2015 (http://shibboleth.net/pipermail/users/2015-September/024218.html). But answer from Tom Zeller (http://shibboleth.net/pipermail/users/2015-September/024220.html) which suggested to use https://wiki.shibboleth.net/confluence/display/SHIB2/NativeSPAssertionExport does not answer Paul's (and my) question.
I configured my SP by the above URL (NativeSPAssertionExport) but our backend application can get only <saml2:Assertion> from SP's URL http://localhost/Shibboleth.sso/GetAssertion?key=...ID=... .
I understand that this is a security risk, but this is the business requirement.
Is the only option to put SP behind the 2nd Apache HTTP acting as a reverse proxy and redirecting SAMLResponses to our application at first?

Best regards,
Roman