Since it's only a baby, go with a tub the size of a 10 gallon tank, rather than a 20 because small snakes stress out in big enclosures. It helps to put crumpled balls of newspaper in the tub to help them feel more secure.

Thermostats are the best route.. an UTH without something to regulate it will burn your snake. Rheostats are ok for awhile if you're tight on budget.