Will he potty on this?

My pigs do pee in there cozies. But my pigs mainly like to pop there they have many spots to hide but each of my pigs had there own comfurt zone where they like to pop and pee a lot and in my opinion thats great, but you need to clean it out atleast once a day or more if possible.

And about your cage smelling so bad are you using a C&C cage that meets requirments for your pig or are you using a pet store cage if you are thats probably the reason when I used them my cage smelled horrible 12 hours after I cleaned it so i ended up cleaning it in the morning and the evening.

Pigs do like to go potty everywhere and anywhere, and their bed is no exception. If you decide to get your cavy a cloth bed, make sure the lining of it is fleece to help repel the urine and keep your cavy dry.

Mine all have beds and just love them, but I do take them out daily and wash them all and replace them with dry ones. It keeps the smell down seeing the pigs spend a majority of their time in their beds.

Yes have 2 beds so you can wash one etc. Do you have a litter box under the hay rack? that too will hold much pee and you can clean it out daily if needed. I use Yesterday's News and a top layer of kiln-dried bedding in my litter box. I freshen it every other day by scooping out the wet YN and replacing it with fresh stuff. I completely empty it and wipe it out once a week. YN really helps with the ammonia smell.
The smell is from the ammonia of the pee.