Considering the Canadian solution - get permission to enter the zone five minutes out, why couldnt we at least produce an upgraded, minimally intelligent AWIS - like box that can broadcast information on who is inbound, in circuit or outbound when polled by a transmission? Solar power, batteries, a software defined radio dongle and a raspberry Pi computer should be able to do it.
For real smarts, an ADSB data derived voice message.
That could give you just about the Canadian thing unattended.