Couple Corn Questions.

[Serpent-King]

Ok, to start off I own one snow cornsnake named Frosty. It's about 22 inches long now and growing fast ( 2 weeks ago it was 18 inches). Well I have just finished making a new cage for a mali uromastyx I plan to get in a couple weeks. And I had some left over plexiglass. With one of the larger chunks I can make the corn a 2x2x2 cage. Is this good? It seems kind of short for a corn, but also it's pretty wide. Or would it be wiser to hold off and keep it in the 10 until I move my ball python out into a 3.5x2x2? Cause then it will get a 20 gallon instead. Which choice would be best?
Also what kind of substrate does everyone use? I use reptile carpet for corns because they like to burrow. I got a nice snake I wanna be able to see it, not go diggin' in the bark for it. When corns get older do they lose this habit? And is there a more eye appealing sunstrate to use? I really like using repti-bark but that makes it all too easy to hide! So any tips? Thanks for any help.