The first thing to do is to assign staff members to each side, especially mechanics, since you don't want mechanics wandering around trying to get to a ride on the other side. One of the Double-Deck Observation Towers can be removed.
If you have enough money after building more rides on each side, build a footpath across (with a food court in the middle) so guests who do not want to ride the Chairlift can get to a good ride on the other side.
Continue to expand, and soon, you'll be getting lots of money. This scenario is extremely difficult, but it can be easier if you advertise all the time and build tons of rides.