Add a UTH + thermostat for heat, some substrate, hides, digital thermometer/hygrometer, temp gun, and water bowls, and you're done.
For a baby just get a smaller tub.
I agree with bcr. Tubs are just easier. When you use a tank you tend to turn a low maintenance pet and turn it into a high one. If your prize form over function though a tank can work but I definitely would set it up early.