Admittedly, the stock fusion system is quite elegant - fusion cells always generate the same quantity of plasma and only the temperature of said plasma is amplified by the neighbor connection bonus. But if you still find creating energy in such a way cheesy, you can forgo the temperature rise and tie your fusion power output only to the number of cells spent. This is an analog of my other mod Thermodynamically Compliant Reactors. This one however requires the Space Age DLC.