If I leave my guinea pigs like this will they pee in their cage?

I want to let my guinea pigs run in and out of their cage into the playpen I have for them (whilst im in my room, where their cage is) and so they have more space to play in since their cage isnt actually big enough but I cannot get a C&C cage, but will they pee in their cage or their playpen? because Im a bit dubious about having guinea pig pee all over my floor, you can pick up poo but the urine makes a big mess!