PfSense redundancy with two different boxes using VLAN based interfaces

[CDuv]

I know there are multiple topic about how pfSense can handle CARP-based hardware redundancy (eg. Is CARP hardware redundancy possible with 1 WAN IP? and others I can't remember).

But when the question about mixing different hardware occurs, the answers is: "as long as they have the same number and order of interface, everything is good"

In my case I have a working multi-WAN pfSense setup with 2 physical network cards where one (em0) is for the LAN side and the second (em1) is split via VLANs for the WAN side

• WAN1 = VLAN 3 on em1

• WAN2 = VLAN 4 on em1

• WAN3 = VLAN 6 on em1

I would like to backup my pfSense with a spare box I have, but it only has one physical network card. I was going for using the "VLAN-trick" again and configure it as follows:

• LAN = VLAN 1 on em0

• WAN1 = VLAN 3 on em0

• WAN2 = VLAN 4 on em0

• WAN3 = VLAN 6 on em0

But I don't know if the pfSync protocol will propagate from master box to backup box the NIC interface configuration (the content of tabs "Interface assignments" and "VLANs" of "Interfaces" administration GUI): thus asking the backup box to use "em1" which it don't have.