To get sticked I think there is some work to be done by other member. I fell alone with this topic so I give up for the moment (other things to do like my wedding for example).
I think the best way is to use the appliance part of pfSense build tools, we also need a lot of patches from last kernel and xen devices (the xn network device for example that need some improvement if we need to manage VLAN inside pfSense or QOS with bandwidth tweaks).
Feel free to try and Improve the receipe, if this topic is moving on, I will do my best to continue my work.