Don't feel too bad, you do have log hiding places for them and that's important. I would suggest adding wooden shelves that attach to the cage, this gives them more places to jump to and they can also chew on them. Chinchillas like to jump and don't really need the ramps. Also someplace flat would give their feet a rest from all the wire.
If you wanted to use the fleece liner, you could put dishes of shavings in the corners they pee. That way you just have to clean out the dishes when they get soiled. There's no guarantee though, my chins decided they want to pee anywhere they want!