A lot of good info so far.
Only thing I wouldn't do is use a 10 gal, they are too small and tall to create a good thermal difference between hot and cold sides. A 20 may be to big for a young one, but you can clutter it up good and make them more secure until they grow into it (not a long time).

Another thing I do with all my tanks is to paint the outside of the sides and back, helps them feel less exposed.