What size tub is #4 in right now? If her hide is BIG and she's burrowing I would try giving her a smaller and tighter hide. I think the burrowing my be her way of saying she's not feeling well hidden. It feels a bit odd to say she's big for her tub but also has a big hide AND clutter. I have a very shy super enchi pastel mojo around that size that I had to put in a short little hide her back touches so she feels snug enough to eat regularly.
I agree on trying #2. It'll be easier to work with a bigger snake in a bigger home. Not every snake feels comfortable in something that large. Also, if they're defensive, you may need to cover the front for a couple of days to get them used to it. If they continue stressing and bopping noses on the glass at any movements, you may just need to go back to tubs so you don't risk injuries to the teeth or jaws. Same thing if they refuse to eat, may need to clutter more of just go back to something more snug.
I LOVE that people are being more adamant about larger enclosures overall, but the majority of 'my snake isn't eating' posts lately have been small BPs swimming in large homes. They can definitely be one of those size up enclosures with the snake type and not the they'll grow into it type.