I am not a fan of doggie panties
For Haruka, she hates to be dirty.. so when she has poop hanging her hair (doesn't have that often) she hides.. and feels so bad... So I don't know if dogs would be comfortable with that. I would rather have the small playpen. WHen I was training her, I had shower curtain underneath of playpen. (so you don't ruin carpet or hardwood floor). Then I put one peepad. I try to train her that way. If she made a mistake, I was able to correct her. That was the way she learned. I would avoid those panties stuff.. it is just my opinon.
I know it requires a lot of patience.
Good Luck!