1. Are your temps and humidity good? 78-80F cool side ambient(air) temp, 90F hot spot and 60-70% humidity. Does he have small enough hides on the cool side and warm side? Throw is a couple paper towel tubes or a cereal box. Snakes LOVE cereal boxes for some reason lol.
2. Are the hides small enough for him to feel secure in and closed off enough? A hide with huge doors is not secure for them. Looks like you got a t-stat which is good. 90F is on the floor of the cage? You don't want to take temps from the top of the substrate. Also get digital equipment. Analog generally is off in accuracy.
3. Cover 3/4 or more of the top of the cage with tin foil or thick cardboard wrapped in tin foil or acrylic cut to fit with holes drilled for air. Then what I do for tanks is lay a folded up wet paper towel on top of the cool and warm hide. That should bump you up there. Also use a large water dish and place it close to the UTH.
4. Most of my snakes eat the first day. Depends if the snake looks comfortable. The general rule though is wait a week.
5. I keep pretty much all my cages pretty minimalistic as I like the ease of cleaning. I just give my snakes 2 hides, a large water bowl and in the AP cages, I have shelves for them to sit on and climb on. You can go as fancy as you want but remember, the more stuff you have in there, the more work it will be to keep it all clean and trying to find secret poops and pisses in a cluttered cage can be a treat. I would invest in the second hide for sure and probably something for him to climb on. Reptibark should be fine. I use aspen but after my 2 bails run out, I am going to switch to ReptiChips. I would also definitely invest in a IR temp gun and new thermometers. I personally use https://www.acurite.com/digital-humi...326-00327.html.