I had better success with setting my tent up with metal shelving that went from floor to ceiling and using a "hot/cold aisle" approach.  The intake is in front of the shelves and all the fans blowing towards the back of the tent.  The exhaust fans suck from the top of the tent directly outside.  I also used styrofoam insulation boards on the front of the shelves to block off unused space so it forces the airflow directly through the rigs.

4,500CFM is solid, are you bringing air from outside in and pushing it back out without restriction?  If you don't have airflow to/from outside then you will restrict air movement.  Bringing in air from outside and pushing hot air out made a significant difference.