Your setup plans sound pretty good Hector. The only thing I would add is a temp gun. I love them because I can accurately check the temps anywhere in the enclosure. The only thing I would change is the heat mat. I prefer Ultratherm UTHs over Zoomed especially for tubs because the Ultratherms don't get as hot even in the event of a thermostat malfunction. I've seen the Zoomeds top out at over 130F. The Ultratherms top out around 100F. Looking forward to seeing the new setup and critter.
http://www.reptilebasics.com/ultratherm-heat-pads