I have car meets quite regularly. Usually I rent a car or use a company pool one. The advantages of a rental one is the company won't usually divulge who rented it to third parties although if you work in the hospitality industries it's usually quite easy.
As for finding the address of the registered keeper (not necessarily the driver) from only their index number the DVLA can help
External Link/Members Only
There are some fantastic deals on rental cars at the moment
"You can ask for details of another vehicle’s registered keeper. You’ll need a ‘reasonable cause’, for example:
finding out who was responsible for an accident
tracing the registered keeper of an abandoned vehicle
tracing the registered keeper of a vehicle parked on private land
giving out parking tickets
giving out trespass charge notices
tracing people responsible for driving off without paying for goods and services
tracing people suspected of insurance fraud"
You'd have to lie through your teeth over 'reasonable cause'. Which is probably an offence in itself.
As for using a company car pool car, getting caught kerbcrawling is one thing and wouldn't go down well with an employer. But getting caught doing it in a company car would probably lead to instant dismissal? But of course again, the level of risk would be a lot less with a pre-arranged 'car outcall meet'.