Hi, I honestly don't think diapers is the way to go. It wouldn't be pleasant to have a soiled diaper on and it's no good for their skin/fur. Regarding the poos my goodness all of mine are litter box trained and they still have accidents. I have a mini boom and dust pan I bought at the dollar store and clean up with that.
Are you using vinegar to clean up the pee, it works really well. I spray the stain, let it soak in for a few minutes, brush it, then uses paper towels to soak it up. Just like new.
I have also used the plastic runner (you can purchase at Walmart or any store like that) put it on the rug if they pee just wipe up with paper towel.