Free range litter (re)training problems

My 2-3 year old bun, Hootie has been free range his entire life. He got caged in a large dog crate only when I was gone for extended periods. Now, I moved to a larger place, and I got rid of his cage entirely.

When he had a crate, his litter pan was in there, and he used it perfectly. Even when he free ranged he would run back to his cage to do his business.

Now, when I leave for the day for class and work, I just close him in my room. He has his own little corner with a hay rack, litter pan, water dish, toys, etc. at first he was still really great about using his pan. Then I started to see a few droppings in front of his litter pan. I figured he was just getting used to a move, and just kept putting his droppings back in his litter pan to retrain.

Now. He barely uses the litter pan. He keeps his business in his corner. But it's basically everywhere. I'll clean it up when I go to bed and I'll wake up and have to start my day cleaning up Hootie presents.

I have a few thoughts, and would love to hear what everyone has to think, because this is not acceptable!

My thoughts are that his litter pan is now on a carpeted area instead of the plastic tray it was in his cage. Because he seems to contain the droppings to the carpet I put in his corner.
Another idea is that he is a crazy eater. He flings hay everywhere and throws it out of his way to find pellets that have sunk to the bottom. Once this happens, he decides it's litter and thinks it's fine. This is a large problem because it's not only a mess, but it's a huge waste of hay because he obviously won't eat the soiled hay.
Another is that maybe the litter pan is too small for him? It fills up quickly, and he's very picky about using his pan when too many droppings accumulate. So I usually daily spot clean when I do the rats, and just mix up his litter and take out any really soiled areas.
As far as I can tell, and I'm pretty sure, it's only droppings. He pees in his pan no matter what.
Any ideas?

It might be that he was use to having a confined area that was his, and now it seems as though the whole room has been given to him, so he's probably trying to mark off his territory from you lol

Two things happened simultaneously to your bun 1) a new environment 2) a new boundary i.e. the walls of your room.

I would suggest that you re-teach basic potty manners to your bun, by giving him a space of his own that he knows is his either by another dog crate or cornering off that part with a play pen. Start small then slowly increase the space as he gets better with litter usage.

If you're using the same litter tray as before and cleaning it as usual, it shouldn't be the problem

Unfortunately, your bun might never be alright fully free ranged and might need a clear distinction between his space and the rest of the world to ensure proper litter use. But give it a go and see!

Good luck

Yes my first suggestion is similar. That is to limit the size of the area that he has access too. Whether it be setting up a small play pen around his litter tray or similar. With a smaller area, you should see an improvement of litter habits and after that happens, you can increase the size of the area a little and see if it continues and slowly increase the size of the area if he still has good litter habits until he's back to accessing the whole room. The other option is as you mentioned, to get a bigger litter tray, which could be quite beneficial if he's just fussy about the cleanliness of his pan.

How long have you been in the new place with him having access to the whole room? It's quite possible he is just marking his territory in this new space if you've only been there a week or two. Sometimes it goes away on it's own, but otherwise reducing the size of the area he has access to and slowly increasing is the best way to combat it before it becomes too much of a habit.