i think it is a GREAT idea as long as it works! you will have to let us know how it works for your babies.
it reminds me of when i had my italian greyhound. he was soooooo hard to potty train. i blame myself for that tho. anyway, he loved to pee on my carpet. so my friend suggested i get a scrap piece of carpet and take it outside with me LOL. i never did it cuz i didn't want to encourage him to pee on carpet...but it was hilarious