Definitely get a large sign and put it outside the theme parks, or as close as you can get to them and advertise your canoe rental business. See if you can improve that business.

As you've got two theme parks that means a lot of people coming into your town. Find the highways that they mostly come in on and look around for a business that you can set up/buy along their path and sell ice cream/other food.

How many people are expected to come into the theme parks every year?