I've only hit them a few times, but a Cayman ball is difficult to use in the wind. Because it is so light it acts somewhat like a wiffle ball. Hitting it just does not seem like golf to me. I would expect most people to play your proposed course as a par three course.
What about just creating an unusual number of holes to fit the available land? Ideally it would be a number that divides into 18 (such as 6 or 3), but 4 or 5 might be just as enjoyable.