IPSec LAN2LAN connection using a transfernet (pool)

[Jürgen Garbe]

Hello,
I have to build up a LAN2LAN connection through an IPSec tunnel.
Let's say our LAN (A) is 192.168.0.0/24.
The remote LAN (B) to connect to through the internet is 10.0.0.0/24.
The customer requests us to NAT our LAN to a pool: 172.18.0.232/29 (T) (some kind of transfer net we have to use).

I have no problem to fulfil these requirements using 2 PFsense instances:
The first one is doing the NAT (using outbound NAT on its WAN interface) and the second PFsense instance does the IPSec tunneling job between the transfer net (T) and LAN B on the other side.

But I am failing to do the job using only one PFSense instance.
In the phase 2 paramaters there is no possiblility to use such an limited address pool as transfer net (only 1:1 or 1:n).
So I tried to do the NAT again using the outbound NAT function on the IPSec interface, but no way, the traffic is not routed to the IPSec interface but comes directly out of the WAN interface.

Any ideas/hints?

Regards

Juergen