I dont think you have enough intake and exhaust.4-3inch holes will not exchange the volume of air you will need to.Those small fans, how many cfms are they.How many cfm fan will cool the light?Those odor cfl lights are not proven to do the same job as a carbon filter.You would have to have about 10 or 12 of them.then you have a heat problem.They give off more heat to clean the air.I would get a 4" can or vortex fan that has 172 cfms and pull the air from the cab through the light and exhaust it through the carbon filter.Down in the bottom install two 8"x16" vents to suppy intake air.One oscillating fan in the cab blowing 24/7.No heat problems plenty of fresh air circulating and no smell.Do move that power stirp,it will get wet sometime for sure.Hope I didnt throw a monkey wrench in all your plans,But you will like it better. You have the right idea you just have to change it a little. PEACE