Liz, some friendly advice.. You need to get your head around how tourist transport services work here.
It's pretty evident you want to go the "Executive Luxury Route" with those big SUV's with leather seats, tinted windows, and ice cold A/C.
I may be wrong, but as others have said, you're not going to find many of those on the North Coast. (There are Executive services out of Santo Domingo, but those cost an arm and a leg)
I'd be willing to venture your only option is going to be to use Taxi vans that belong to the airport or Cabrera taxi unions.
I'm not saying it will happen for sure, but there is a good chance that if you don't use a company that belongs to a union somewhere, the local guys are not going to appreciate it.
I had a 15 passenger van with an English speaking driver a few years back, and he was "sniffed out" within 2 days while driving in Cabrera. (He was doing pickups at the airport for Orchid Bay at the Puerto Plata airport) Cabrera is a VERY small town.
They were nice enough to warn him off, and told him if he was seen again transporting folks, it could lead to problems.
Setting up transport services like you're looking to find is a lot different than the way they do it in Ohio.
You'd be well advised to have somebody help you out who knows how things work here in the country.