What is the wattage of your heat bulb? And do you use a black or red bulb at night so it doesn't bother him?
Just a reminder that the tank temp shouldn't go below 75Fwith a constant heat source that shouldn't happen (I would think). I have both a lamp with 50W red bulb (to up the ambient temp) and a UTH with thermostat, which works well for me. The ambient stays at 80F, and the heat mat is set to 89F (so it goes up or down about 2 degrees). Although my BP never burrows to the heat mat, and is in a different hide every day
As everyone said, I definitely think he could use some more foodhe's not starving, but kinda small, to be honest. But every snake is different. You've already said you'll get that sorted, so that's good!
I definitely think your snake could just be curious and roaming; mine does that too. Especially if he's still out and about after you've given him more food and done a few other suggestions.
Good luck!