No it is NOT generally recommended to keep multiple animals inside a single enclosure. The general rule of thumb I use is the length of the snake should not be longer than the two short sides and one long side combined. I like to go a bit bigger myself, and say one short side and one long side. I suspect you will not have much issues with heating and humidity where you are so this seems like a great plan. Black paint on the outside of glass makes a really nice glossy black interior. It scratches easily if you mess with the outside much however.

Question were you the person ages ago whom was planning on feeding chicks due to the difficulty in getting rats? If so how is that going?