This is an idea for that park:
The money problem can only be solved by a rich dude. Rich dudes are building dream tracks all over the country. A dream track in paradise is possible and it can make a profit.
Space is a big problem on a small island. Build a small track. 1/8 mile drag strip with road course. Infield pits and kart track. 1/8 mile dirt oval with infield motorcycle course. Short sand drag strip. Separate entrances for street and dirt tracks.
Noise is a big part of racing but is a bigger problem for the people who live near a track, thereby greatly reducing the possible locations for a track on a small island. Strict, self imposed and enforced noise limits. Air boxes and quite exhausts on all vehicles. Keep the race vehicles as quite as cars on the show room floor. Stock dirt bikes will be too loud but aftermarket exhaust makers can solve this problem. Apply this rule to generators too. A nice spin off of low noise is the PA system will cost less and you will be able to hear it.
There are fools who will say that it’s not racing without noise and that they make more noise with their street vehicle now. There are fools who will say that 1/8 mile drags are not real drag racing. There are fools who will say a ¾ mile track is too small and that the straight is not long enough. There are fools who will say all kinds of things about how this track is not good enough. All true, but you don’t have a track now do you? This argument leads to what you have now, no track. These fools did not race when you had a track and they won’t even if they lived in a place with a track. There are fools, don’t count them.