Many overseas airlines can do that and it works well for them. 
The best implementation I've come across was with CX in HKG where a staff member was at the start of the queueing area, checked everyone's BP's and directed them in the right queue.
The way VA has organised the general queue to be inside the waiting area (and priority enters from the concourse) would easily lend itself for checking: have a staff member at the edge on the concourse checking the eligibility because it'll be easy to divert the general boarding away from there priority queue at that point (instead of the scanning point).
