What size should I feed my ball?

Btw, I said he was well-fed, but on closer inspection he seems underweight. His skin is really loose and his sides are a bit sunken in. He's not, like, starving, but he's thinner than I feel comfortable with, so I'll be happy when I can get him eating.

Well if he was on live, and with what you've said i would recommend getting 1 of each. Simple because saggy skin is shown for weight loss from his initial size, So you dont wanna play the patience wait game to long with him to get on F/T. The switch honestly isnt Hard at all, its the snake, i was able to get my lavender spider baby from live mice. to FT rats in 2 feeds... first week frozen mouse, took it.. second week Live rat pup took it, 3rd week frozen rat pup, now its eating every week, (1 with denial and i was out of rat pups so offered a small weaning and she must have been scared and defensively struck it) So because of the stress from move, keep his feeding the same for the next feeds Once on track and has a good eating habbit (3+ consecutive feeds) I then would make the switch to F/T. Or even go from Live 3 feedings to Pre killed 2-3 feedings (simple DiY gas chambers to euthanize rat harmlessly) and with 3 consecutive feeds then feed him F/T... Owning a bp is one thing. Patience!!!! ​ As well as not freaking out or being a worry bug if he skips 1-2 meals!

Also looking at that "home" not that its bad, but please please please get him a hide box. Reptile basics black hides are amazing! and that will 100% help him eat