Ah yep, both those hides are too big. The fake rock one could maybe work if you put some crumpled newspaper in it, but I would just go out and buy a couple plastic flower pots and cut/solder a doorway in them. Young bps outgrow their hides pretty quickly. Like I said you need hides that are fairly snug. Another thing....half log hides are really poor hides for BPs, probably anything. They are open, so BPs don't feel secure in them. Since you have a young BP, he's probably going to be pretty finicky about his enclosure/hides. When BPs don't feel secure they won't eat. And yes they will starve themselves to death, don't let anyone tell you differently. However, if he's an easy keeper and eats for you, don't bother changing the hides, other than getting two identical ones, you could still leave the log hide in there to take up space.
After you have the hides sorted out, you could leave them in there and put the flower pots where those two hides are (assuming one is on the hot side and the other is on the cool side) put some fake plants in there to fill up the space. If you leave those two hides in there it will help fill up the space as well. I doubt your BP will chose one of those hides over new smaller hides, but if he does take the old hide out (they will choose the hide they like best regardless of their health-that's why you need identical hides).