I use a few sheets of newspaper to line the bottom of my litter box then put some hay on top. For some reason Rocky likes to 'go' wherever there is hay or newspaper. If I dont have something on top of the newspaper he will tear it to shreds though lol
Doing this I have to clean it twice a day, but I haven't got much option at the moment because I haven't found anything else that is suitable. And I have just got him little trained and dont want to have to start again if I change his routine again.
As for the stinking, what is it that smells, her number ones, twos or just herself? If it is her then it might be her scent glands, or she might have poo/pee stuck to her. If it's her poop it may even be her diet.