I use paper substrate, Uline printless newspaper, because it makes cleanup and keeping things clean a breeze. I use it in all my tanks - 9 of them (7 snakes and 2 lizards).
Frank is a Northern Blue Tongue, so he does not have high humidity requirements and paper substrate and a small water bowl suit this well.
Common in captivity to have to trim BTS nails, but especially without substrate BTS can really dig in. Even, then, your will probably have to trim occasionally. Unlike monitors, where you shouldn't trim the nails, BTS nails will curl under and create issues if not kept trimmed. BTS are ground lizards and do no need the nails for climbing, like monitors. When I cut his nails I cut just below/above the cuticle, depending on how you look it. Either way, it's as close to the hand/claw as I can get without drawing blood.