If you are going to use disposable pads, then the litter box idea sounds the best so that they step in and out when they go. Penny will sometimes go right on the edge of a pad on the floor and urine will be under the pad also. (We don't have a litter box because we are about to switch her to the Pet Loo instead.)
We purchase the human bed pads at Sam's Wholesale. They are much cheaper than the dog pads and larger too.
Penny will only use a pad 2 to 3 times depending on where the wet spots are. She has to have enough room on the pad to walk around to go or she will go next to the pad instead. This is why we can not get off day 0 on the YT potty log.
I think we would have to have two litter pans if we were going to go that route. We are really hoping that the Pet Loo will enable her to go several times a day in the same spot. I will report how it goes a couple of weeks after we get it.