Seems strange as we have all types of ports available (email, ftp, http, etc) but only http can be used via RI. When you tell managers you can’t implement ftp they wonder whey they spent millions on the software, so it’s doubtful buying another proxy is doable. 
One thing I briefly thought of is putting a service on the proxy that can be invoked via ftp (a regular ftp port) that will pass it to the http proxy port to get to the internal IS. We’re dealing with a bank with limited options (ftps at this point).
#webMethods#webMethods-Archive#Integration-Server-and-ESB