Wats up there hempplaya,
Yo it's like your reading my mind,LOL .My box measures almost the exact same as yours and I placed a fan in the lower right side of the box with a vent on the upper left side which causes the air to blow through and out the vent with no problems.I originally started out with cfl's which were great,but then I up graded recently to T5 flourecent lights which kick major butt.The box is also lined with mylar which makes for really good reflectivity.The reason why I put the fan there was simply out of convienence and the exhaust pipe in the upper side of the cab because I figured heat rises and the fan blows out any heat and provides for good air movement.If you close the box and place your hand over the vent you can feel the air comming out because of the was it is set up as well as the size of the box.If heat is a concern for you and ya' want to use flourecents look into the T5's which are pretty affordable to buy as well as run and let out hardly no heat :thumbsup:.The way it is set up with 5 T5's running about 3-4 inches above the plants the temps usually stay from 78-about 84 depending on the temp of the room the cab is in.Good luck,and keep me posted on what you decide and how it comes out.