You're gonna need to find out a few things:
1. How much land is available. People aren't going to travel to Jamaica for <5 miles of trail.
2. What is your annual budget for maintenance?
3. Professional trail builders typically charge from $5-$14 per foot depending on the topography. That's a stateside number and being out of the continental US is gonna have to include food, lodging and travel. Along with equipment rental and fuel if using machines. Machines will make the time frame much, much shorter.
4. This should probably be #1. Local ordinances/statutes on liability. If you're doing this as a non paying gig then the liability is much lower. If this is a fee based endeavor than you're going to multiply your risk and will most likely need some kind of liability insurance policy. Local statutes will dictate this.
5. Are there any environmentally sensitive areas on the land or any significant archeological sites. That will complicate things a bit. And then there are land and water quality issues. Local government would be the place to inquire.
And that's before laying one shovel to dirt...
Good luck!
BTW you should do it in St. Croix instead.