Definitely skip the taking him out. The stress will more than negate any potential benefits from UV to his immune system, which are very unlikely to be strong even if existent because they are nocturnal. A broad spectrum antibiotic is probably what is being used which has a good chance of being effective against all of the listed infections, just depends if any of them happen to be viral or resistant to the particular antibiotic, but more likely than not, it's all bacterial. Keep things as clean as possible, disinfect the water bowl daily, and leave him alone and cover his tank as much as possible to minimize stress.

Beyond that, you can use topical treatments on the wounds and the potential mouth rot, but for only "potential" mouth rot in a snake that is already on antibiotics, it may not be worth the stress, and it's hard to know if topical treatments will be ok on the bite wounds without knowing how deep they are. I'd make sure to consult with the vet on any additional treatments. Although if the vet advised you to take him outside on sunny days, you may want to get a second vet opinion.