[SR-Users] help to configure topos module configuration

Caller <--> (internal_IP) Kamailio (external_IP) <---> Callee I have this set up of kamailio with 2 interfaces. i use topos module for topology hiding and what i want to do is to send external_IP in Contact Header of request relayed to Callee and internal_IP in Contact Header of response relayed to Caller. i noticed that : when i use topos module with contact_mode to 0 all Record-Route and Caller Via Header are removed and thats great. but i dont find way to put 2 different ip addresses in Request and Response Contact Header? when i use contact_mode to 2 Record-Route and Caller Via Header are not anymore removed thats bad for topology hiding. And its seems we can not use $xavu(_tps_=>contact_host) parameter of module to put 2 different ip addresses in Request and Response Contact Header. What i want is : - remove all Record-Route and Caller Via Header for request like when contact_mode to 0 - and put 2 different ip addresses in Request and Response Contact Header is it possible to achieve it ? Thanks.