snat through ipsec vpn in transparent mode

[Stefan_Michiels]

Hi, we have changed from netscreen(juniper) products to fortigate units since 2 years. Now we have changed almost all but the last one's are in transparent mode with snat on the ipsec. I know that fortigate doesn't support that, snat is possible in  transparent mode for traffic policy's but not for a policy with ipsec. Does anyone know of a workaround ? I was thinking of using vdom with the transparent vdom as root and nat one to setup the vpn. This works but I can't route the traffic from the transparent mode to the nat vdom with a vdom link. Anyone can help me ? The vpn is working fine, i've done some test changing the lan but its impossible to change the lan's at the client sites.

example of what I'm trying to do, 

lan client 172.16.15.x snat traffic to 10.4.18.x before sending it through the policy based ipsec vpn ( transparent mode )

Thank in advance.