Hi,
If you want to send JSON part as context with application/json like REST step, then it is impossible to send JSON request by using the "HTTP/HTML Request" step.
But you can send the (post) parameter style like <parameter key name>=<JSON part> by using the "HTTP/HTML Request" step.
Why cannot you configure SSL details in local.properties file?
Technically it is possible, please refer the this documentation.
Cheers,