This is my unprofessional and uneducated guess so i just might be wrong but i would stay the thicker cause its stronger and also a burn i would think could start weighing a couple pounds that along with beding and hides and decor would weight it down a bunch as for the sides and top they can use the thinner if you would like cause they dont need to support so much weight. Again is my guess im pretty sure im right though better let someone say something before you make your decision.