Andrew, nice to see you've joined the site. Andrew lives by me and was going to buy my 20L tank off of me, went with the 55G instead and Ive been trying to help him get the set up right. I told him to cover the top and sides, gave him a spare fixture&bulb, some sphagnum moss and a terracotta pot to use as a hide. Also advised the Acu-Rite. When my little one gets moved from tank to tub I was gonna sell him my CHE to use with the UTH. Advised against the hot rock.

Andrew, if you wanna head the other route with proper undertank heating, I have a spare sheet off 11" Flexwatt, 12" long already wired up. Thing is you're gonna need a thermostat for it. PM me on here.