This may not work for you - but I have a doggie door - out to a very secure, locked and gated back yard. I know most of you would not or could not let your babies go out unattended, but I can. It really helped me a lot. Rowdy had lots of accidents until he could go in and out the doggie door by himself. Rexy basically followed Rowdy's lead and had very few accidents in the house, except that they both like to "go" (mostly poop) on the carpet in my mom's room. The rest of the house is wood floors so I say that they think her carpet is grass
(no, it's not green, but feels kinda like grass, don't ya think!
) Rowdy does mark occasionally, but he is not neutered so that is expected.
Anyway, the doggie door saved my life!!!