Mobile Search in the DMZ

The documentation for Enterprise Vault Mobile Search says that it is recommended to install the server in the intranet and apply a reverse proxy in the DMZ to facilitate outside connections.    My problem is that my customer doesn't think this is very secure and wants to put the Mobile Search server in the DMZ.   Does anyone know what ports are required to be open in the firewall between the Mobile Search server and the other EV servers?   Is it just an https connection or does it require everything that would need to be open if the firewall was between two EV servers?

thanks,

Mark