IMHO a network that radio only and not on the internet either the sub net should be using 10.x.x.x, 192.168.x.x or 172.??? address. If later they do connect to the net and then try and route it could cause issues.... Like companies that found that out when they had used 1.x.x.x which is assigned to the US DoD (I think)
Alternately a 44net class C could be set aside for un-coordinated un-rotatable use.
Lin N4YCI