With your boat........generating a larger wake sounds like it may not be an option as alot of fishing boats are designed to have very little draft and do not make much of a wake especially given that you can't push the hull down lower in the water or change the trim / attitude of the hull when on plane. Also as it is made of "plastic?" adding weight / load may be a problem also due to limitations of how the boat was built. That said, without a "ramp" for you to generate lift, your focus will be, as the others have said, to learn to edge effectively and load the line so that you can generate the most pop / lift given the wake you DO have. There are some great instructional DVD's and probably online articles you can find to help learn tips / techniques on edging. That will help... However without alot of wake size, learning really advanced tricks may be a challenge. Wakeskating is a very legit option...and maybe exploring the trim / attitude of the boat to create a larger wake if you can do this with your current boat. Ultimately you just need to maek the most of what you have....have fun with what you have.
Sorry this is not alot of help...but hopefully this will give you a bit more direction.
Performance Ski and Surf. www.perfski.com