Rainbow boa terrarium questions

[Snakesitter]

Size
Aim for at least six square feet of floor space, unless you plan to move up in sizes as the animal grows. (This is based on the "one square foot of floor space her foot of adult length" rule.) I actually go higher myself, and offer adults eight square feet. Height is not a concern, one foot is fine. As was noted by others, just be sure to add extra hides and other cover.

Heat
A radiant heat panel is fine, just a bit more pricey than undercage options.

Light
I generally do not recommend enclosure-level lighting for this species. They are shy and nocturnal by nature, so bright light is not high on their list. Just use room lighting.

Thermostat
I tend to go high-end, due to the increased accuracy and reduced risk of failure -- and because I buy the units with four controllers in one box. The Herpstat 5 is my unit of choice...though it's not cheap.

Good luck!