Do not be intimidated by the fact this is the last scenario. The only difficulty here is the terrain. You start with a path system and a chairlift already in place, a decent amount of space to build in, and an incredibly low guest goal for the time given, so this scenario should be easy.
First, while the game is paused, adjust the price of the chairlift and set an entrance fee if you want to. Set your research priorities to thrill rides to get more flat rides. Keep in mind that, after 4 years, you will have researched (if at maximum funding) all thrill rides, gentle rides, and roller coasters available. Now hire some handymen and mechanics, zoning them if you wish. Now unpause the game and remove or block the path on the top of the rock, leaving only the path to the chairlift open so that guests can walk up and down the rock. Next, build some stalls and bathrooms at the park entrance and at the top of the rock.
This park has three areas for construction: the top of the rock, the desert, and inside the rock. You have four years to complete the scenario, so you should really try to use all three areas. The strip of desert around the rock you own is narrow but conducive to building flat rides; however, you may want to save some space there for paths as well as the stations and queues of tracked rides that tunnel inside the rock. The space on top of the rock is best for tracked rides, but you may also use some of its flat areas for flat rides. Building inside the rock is not easy, but you should build some of your tracked rides there to increase their excitement ratings and ensure guests will ride them in the rain. Log flumes and river rapids are popular in the desert and have high capacities that help prevent overcrowding, so you should build at least one of each. If you research roller coasters, you will eventually get the Vertical Roller Coaster; build one as soon as you can since you should easily be able to get an excitement rating of 7.00 or higher with it.
As you fill the space on top of and around the rock, you may notice guests and mechanics getting lost. To prevent this, build additional paths from the top to the bottom. Also, consider zoning your mechanics such that they do not need to move between the top and bottom to reach the rides they must inspect or fix. Consider doing the same with your handymen.
Your guests here are quite poor on average, so you will need to keep your prices fairly low. This, combined with the low maximum loan of $15000, means finding money for constructing big rides will be difficult. This should not be too much of an issue, as the low guest objective and the limited land available should encourage you to build mostly shuttle coasters and flat rides, but you should still be aware of this issue and be careful.
Assuming this is your last park in the game, you may want to try the following. In October of Year 4, build a Shuttle Loop, but do not open it. Change the launch speed from 40 to 60 mph. When you reach October 30th, click the amber (test) light on the ride. If done right, it will crash right as the scenario is completed, producing a firework-like show. Congratulations on beating the original game!