I agree with the crating suggestion above. I tried this on a weekend when I had more time with her. . It didn't totally train her, but it got us started in a good direction.
And I know what you mean about feeling guilty 'cos they are in a pen/crate all day. Molly is in a crate while I work all day. I felt the same way (still do sometimes) but there are times I've got other things to do and can't watch her 100%. If I crate her for a 30 minutes, I can get some of my stuff done, then spend one-on-one time with her. She may be back in the crate after that again for me to get a few more things done, but then she's back out for playtime with me. The time that she is out now is getting longer and longer as I can trust her a little bit...not on the carpet though!!
I'm not that brave yet!
Good luck, and let me know how it goes!!
Carla