As I said when you asked me to post here, I can't really come up with anything reasonable, more dirty and really much different from what Fiona already posted, so I can't really take full credit from this. It's mostly just little upgrade for her dare, so if you fail to do this, you should do a punishment from both of us
You still fill the bath with filth like before, however when your first add some pee and scat at the bottom, you should already take a quick bath in it. First mix it well with your hands and then lay there first on your back for few minutes and then on your stomach (at this point it's probably still pretty empty)
After your bath, dress up with wellies, rain pants, raincoat and waterproof gloves. Use duct tape to seal all the joints so you won't contaminate your house but the filth brew nicely underneath.
You spend day dressed like that, but whenever you need to pee or shit, remove all the clothing and kneel in the bath to do it. You are allowed to clean the outside of your clothes if needed.
Optionally there are few things you can add to the bath:
If you can, freeze all the cum you produce before the task and add all that cum into the mix. It gets nice and sticky
You can also gather some cat/dog etc scat from outside to add to the bath to get more stuff into it. However if you do it, I wouldn't recommend eating any of it. Instead you can take more portion of your own filth to separate bowl every time you produce it and swallow that at the big bathing at the end.
Is it hard enough now?