If going the tracker route then you may as well but a decent one trackers nowadays not only track the van they allow you to plan van maintenance as they record mileage, track your vans speed, plot fuel consumption, time van idling and alert you to route deviations. Newer trackers can all now be accessed through a smart phone a friend of mine who is a manager of a small haulage company has his vehicles tracked and his phone will alert him if-
His drivers are reaching their divers hours
His drivers are consistently exceeding the speed limit
Excessive idling
His drivers deviate by more than 5 miles of the planned route
His lorry's are coming up to service mileage
Any of his vehicles go to an employees house
As you can see he doesn't need to constantly spy on his workers when the tracker does it for him and all of his employees know if one of them alerts pop up and its not something planned through work their phone is going to ring and ask them to attend his office next time they are in the yard.
Thing is they are all well aware of the trackers etc but must be unaware that phones work in other country's because when we went on holiday in the first 2 days he got about 5 alerts and had to phone and warn his employees not to try and pull the wool just because he was on holiday and they would have to explain themselves once he returned.