Anthony, You may find you do not need additional fan by keeping laptop clean and using it on a hard dust free surface. Using laptop on blankets,pillows,etc. will clog computer up very fast with lint, dust, hair and fibers, no mater how many fans you have. Laptops have have vents located around the case allowing airflow crucial to the cooling of internal components. If these vents become clogged, or if heat-generating parts become covered with dust, the fan cannot cool the components properly. Lint/hair/dust can accumulate preventing air flow around the cooling fan blades, on mother board, heat sinks,etc., causing the fan to work harder and potentially cause overheating laptop. If there is dust in the vents, you should clean the laptop by blowing/vacuum out the dust and if possible from around the fan and heat shield weekly. This prevents dust from accumulating for the most part inside laptop and maybe a yearly partial tear down and complete cleaning.
External cooling mats can help, most importantly though keep laptop clean, for free air flow.
I hope this helped you out, if so let me know by pressing the helpful button.