If you don't need to save space and you can keep the humidity up in a tank that will work just fine. However I could never keep the humidity correct when I tried to use a tank.

I personally started with a 28 quart tub and if the humidity is too high there are several things that you can do: drill more holes, move the water bowl farther from the heat source, or use a smaller water bowl. Boas don't need to have a bowl big enough to soak so that shouldn't be a problem.