Clumping litter? this was a red flag for me, even on this site:
The “Prepared” Litter Box
Litter: My favorite litter is compressed paper litter like Yesterday’s News. Don’t use any pine shavings or cedar wood shavings or any clumping litters – all very dangerous. However, dried pine pellets like feline pine or wood stove pellets are okay.
Include Hay: Make sure there is fresh hay in the box. Bunnies poop and eat at the same time.
https://binkybunny.com/BUNNYINFO/tabid/53/CategoryID/5/PID/940/Default.aspx
I did a quick search to try to find a successful story of using such litters:
When I first got my rabbit, Frodo, his former owner surrendered a large container of perfumed, clumping cat litter laced with tiny blue crystals. She explained that she used this litter instead of standard rabbit bedding because it absorbed odors better and was less expensive. I discovered, after talking to several other rabbit owners, that it’s not unusual to favor cat litter over ordinary bedding materials. I’ve even used some types of cat litter for my own bunnies on occasion. But is it really safe to use cat litter for rabbits? Here are some points to consider.
3. Clumping cat litters can cause fatal blockages. If your bunny eats a clumping cat litter, it can form a large clump in his digestive tract, preventing the passage of gas or feces. If this happens, your rabbit will either experience intense pain for several hours, followed by a difficult, traumatic, life-threatening surgery– or, worse, he’ll die. This does happen to many rabbits who are exposed to clumping litters.
4. Non-clumping clay litters are still a potential danger. Many clay litters are exceptionally dusty. If your bunny likes to dig, he may kick large amounts of fine particulate matter into the air. When this enters his respiratory tract, it can cause intense irritation, leading to coughing, bronchitis, and even pneumonia. Prolonged exposure to dusty clay litters can cause your bunny to experience life-threatening respiratory damage.
http://voices.yahoo.com/can-cat-litter-rabbits-10337505.html?cat=53
(I would read the whole thing but I did want to highlight that to you)
I am not sure what you mean by soup. I have the wood stove pellets since I was told it absorbed more then paper like newspaper. Put that on the bottom then hay over it and I have a completely dry box. I am not completely sure how it works with a rabbit that big though, most likely it means changing it more often then others while having a bigger box. A bunny that size might do better with a hay rack over the box over then completely stuffing the litterbox with hay.
uti is a concern with me since most of the time, the ‘normal’ is to have one spot. Even in the litterbox with my rabbit, the poo might be in different places but the pee is in the upper left corner. I tend to put a bit extra litter there from noticing that, and when cleaning it out that corner is the only thing that sticks to the bin after pouring it in the garbage. (clump of wet wood)
stray poo like a few here and there (my rabbit does it) seems normal. I mean very few like maybe 1 pellet every few days for mine.I once picked up 5 in a day but i do not know how old some were. I limit the stray hay on the floor in her pen area and i never seen a repeat of that many (Plus I look more carefully day by day)
Knowing you use that kind of litter too I would strongly suggest to see an exotic vet (Remember normal vets are a no-no)