Welp If you do an internal pump your running a big risk of a heat issue, a pump that big to run that tank for SPS is going to produce some heat, DONT rush with this cause you might regret it in the future. You dont want to get a chiller I remember you saying, well with the lights, pump, power heads or Tunzes you might need to get one. Maybe not, but you dont want to run that risk when everything is done. I think Rob will agree with me on this...what int pump are you using now?? My tank runs at 83 almost 84 during the day and most of my stuff is ext pumps and my Tinzes produce VERY low heat transfer....Plus my canopy is wide open on the top and back of it, your in inclosed except for a little area in the back...
Im just trying to save you a HEADACHE in the future!!
Also remember that everything is in your stand also with not the greates air flow, make sure you have some FANS on hand but running alot of fans might be loud....