Hi
1: I hope you are not doing any interface based NATing (DIP,MIP,VIP) on the firewall interaface for IP 188.x.x.235.
2: Your router A would have a route to send packets destined to the IP 188.x.x.235 to the SSG140, right?
3: Router B is connected to the SSG140 so I am considering they also have IP connectivity.
This should work if you have proper route on the SSG140 to send 188.x.x.235 traffic to the Router B via Eath4. Or do you problem that Eth4 doesn't have a public IP on the Eth4?
Thanks,
Vikas