Never use ifconfig aliases. They won't survive a reboot, aren't necessary, and is the wrong way to setup additional IP's on pfsense. See the Virtual IP page. Then look at the NAT page, Outbound tab. You'll need to enable Advanced Outbound NAT, and put in your NAT rules as desired.

Thank you,
now 1:1 NAT works!  :)

I have not used Outbound tab because from which I understood "Automatic outbound NAT rule generation (IPSEC passthrough)" is sufficient.

I also had to create a rules on the WAN interface to allow traffic from * to the destination internal address, it works, is it the correct way to let packet pass?

Thank you in advance.

Davide.