Hi ashari. My female chinese comes out a few times during the day, goes straight over to her toilet roll tube and uses it as her loo!
Which is great because I can see exactly where she pee`s and how much by the stain it leaves! She does pee in her wheel but not greatly. I too wash her wheel every three days or so depending on whether it needs washing or not.
Watch where he/she prefers to `go` and place a toilet roll tube or something similar near the pee and see if the hamster decides to use it? Not too sure of a hamster corner toilet would work but I don`t see why not as they do like to pee and poo in sand so I`ve heard!