At first glance, the objective may seem much more difficult if compared to the previous scenarios. However, you start out with 260 guests already and they keep coming due to the pre-built rides, so you only need to attract about 940 more. This, in 3 years, should not be a problem.
At the start of the scenario, you have several rides — two of them are roller coasters, which will be your main money makers for now (so, if you don't charge an entry fee, make sure you charge the coasters properly (between $4.00 and $7.00) to get some income running). Note that both Quiver and Flightmare are prone to Stations Brakes Failure crashes. Flightmare can easily be remedied by setting the coaster to run three 5-car trains; though be sure to uncheck "Maximum Waiting Time" to ensure that they won't stall on the first loop. Quiver, on the other hand, is more difficult to fix, so either attempt on editing it so that trains arrive at the station at a lower speed (less than 29 mph), or remove the second train and cope with the loss in income. Regardless, if you designate mechanics to the exits of both the roller coasters to keep them in working order, you shouldn't worry too much.
Besides, Flightmare has a very high Intensity Rating which can drive some guests off. You can handle it a bit by adding not too heavy brakes before the in-line twist followed by the half loop, in the section which the coaster goes underground for the first time. This will soften the Vertical G's and, thus, reduce the Intensity Rating a little while keeping the Excitement Rating.
The strategy for this scenario isn't different from what you've already been doing in the previous scenarios. Just keep in mind that you ought to build a good ammount of good roller coasters in order to keep the guest counting increasing. There's really no need to demolish the two pre-built coasters to boost your cash early on, because they already provide you with a good income and attract a lot of guests. Just keep on developing your park — close to the entrance and the pre-built rides at first, and then, expanding into the lateral and back woody areas — and being sure your guests are happy.
At first, coasters like Steel Mini and Wooden Crazy Rodent (the latter needs to be researched first) will be perfect for building until you get more money to build a few larger and more expensive models. Also notice that you start out with the Steel Roller Coaster, which can be a fairly cheap and good money-maker if built as a powered launched coaster.
The loan you can take is fairly low (you only get a $10,000 more than what you have at the beginning) but with time you should be making more profit as more guests come in and you build more good and profitable rides.
Thrill and gentle rides should be built as well, of course. Just be cautious when constructing more thrilling rides like the Swinging Inverter Ship — and, if you want, one Gravitron and/or Whoa Belly more — added to coasters, as the park will be filled with nauseos guests. You will have to hire many handymen for this park because of that and, if it's the case that you use the feature, set their patrol areas small.
Don't forget to place shops, stalls and restrooms throughout your park, besides adding benches and litter bins scattered around. As always, do hire a lot of staff and assign patrol areas if needed and safety mechanics to your coasters. Make sure you check on vandalism and litter periodically, in addition to checking if your rides are still workable and having a non-negative income.If you keep expanding and building a plenty variety of rides, the guest counting should keep increasing. It's not hard to reach your objective at the end of Year 1, actually. So you have plenty of time and plenty of free space to build more rides and working on getting more guests. If you really start losing too many guests and your park starts to get messy at the end of Year 3, you can always reckon on advertising campaigns, although it really shouldn't be necessary at all.
The high demand guest should not be a problem — at this point you should've already met previous number of guests objectives within a large and clear gap (all the 3-years scenarios this far can be easily be completed with much more than 1200 guests, sometimes starting from scratch). This scenario is not hard at all and if you've beaten all the previous ones, you really won't have any major problem with it.