(PS - I tried the diaper thing - it did not work as I was desperate to entertained the thought for one of my fosters).
Yep. Diapers generally should be saved for males that have marking issues and not dogs with house-training problems. The reason is because sometimes we as owners tend to rely too much on the diaper, thus not solving the problem. Plus, if she's used to peeing on herself - the diaper will only reinforce this constant feeling for her (of wet) which you want to break her of.