Thanks Gomez, I know that vlans will decrease performance of the NIC, of course.
That infrastructure is located in a Camping, the wire goes underground, no law violation as everything is in the owners property :)
Finnally I changed the pfsense box to the House A.
I created two LANS, one for the wifi camping customers, and another one for the Office in House B.
Currently there is just one WAN working, but when I'll receive the managed switch, I'll create a VLAN in the Office LAN adapter to include the secondary WAN access to the system. I will place the switch in house B.
That one will be used for the Office people, as in peak times the main WAN access is saturated by the Camping wifi customers.
Anyway I'd like to thank all the people that helped me on this. Pfsense forum is an example fo what a community forum has to be.