I recently set up a QT tank for a candy cane basslet, and then for a couple of possum wrasses once he went over to the DT.
I used a 20gallon with a HOB filter. I put my candy cane into it the same day it was set up. Added Microbactor7 as per instructions to help cycle and regularly added it after as well.
Also put in a foam filter (extra aeration plus more surface area for bacteria to grow).
Added a seachem ammonia checker on the front to watch ammonia levels.
First week or so changed maybe 25% water every couple days (which really was just a bucket full. Took water from my DT and my DT got a bit of newly mixed water every few days... I must say the corals all seemed to love it too!!! Those little bits of trace elements in there (and whatever else) really help!
Bare bottom.
Like you I went for some rock in my QT tank... made it look cozy
(not too much)
I had some that I had kept in my sump so that really helped with the cycling. As a matter of fact I never had any rise in ammonia/nitrites/nitrates that I saw... and I did run some tests. (That candy cane basslet was just too expensive to chance it lol).
I also but some of that barnacle rock in there... great for hiding spots... JL had it.