I don't think everyday tourist will be interested.
Getting to the right clients that you want is the first problem. How to attract them and get to them. Many that would desire such a service don't make their own plans; they have staff that does it. They don't care how much you charge as long as you are good at what you do and must be willing to take a lot of ?. meet their demands.
Getting to know the people that handle the private planes at the airports might help. The private plane/jet and helicopter companies here and that serve clients around the world. The managers at the upper end hotels. Bank executives. Higher end industry people. Theater managers. CASINO managers/owners. High end property managers such as Sea Horse Ranch?
I'm also thinking of the Australian guy with his loving new Los Vegas wife that are re-doing the Playa Chiquita casino, hotel across from it, show lounge for 500, finishing a mansion and has a private Jet in Miami for when they come to the D.R. I don't recall his name but there is a thread somewhere here on DR1. I also did a little research since we live in the same area. (me thinks he will need a lot of your type of services)
What kind of car, how it is equipped and driver skills for evading situations. Armed and trained with a weapon? Knows how to work with the above people to use more secure entrances, exits and procedures. Is more then one car/driver available for groups?
If thinks keep going the way they are doing here in the D.R., I too will be a client. LOL