Late to the game here, sorry.
A couple thoughts.
Ambient temps and hot spot/hot side seem dead on.
However, 73f is too cold anywhere in the tank.
Coolside for BP should be no lower that 78f.
I keep my cool side around 80f. Ambient temps are 80-84f (big tank so it can vary distance from heat sources). Hot side is 89f.
I would get temps dialed in and then feed.
Read up on proper defrosting techniques. Also, probably need to shake on a tongs for him. Not all BP’s will eat a prey item left for them.
Snakes will thermoregulate even if temps are not ideal. They know they need to cool down, but don’t necessarily realize it’s too cold for them.
Beautiful snake and nice setup.
If if I recall you kept fish, correct?
Me too. I used to breed frontosas in a 240g as well as other tanks.
Reptiles are more forgiving and interactive. However, the attention to detail you need for fish to thrive transfers well into reptile keeping.
Keep up the good work and keep learning and asking questions.
Thunder will do great!