thats the size tank that i have, and it is pretty good for an adult, although a lot of people would suggest a tub setup. i would suggest getting a smaller tank or tub for now, and keep the tank you have for when the snake gets larger. it will still need some clutter to fill up the space, but after you put in 2 hides and a water bowl it doesn't take much.

as for heating, yes its still a lot of air to heat, but i have a 40 watt che that takes care of that problem, although i would prefer to have a bit more powerful one. so there is no confusion, i also have a uth that does the bulk of my heating.