I asked some MVP friends and Sarah Dutkiewicz came up with a great answer:
The web dev in me had to do some exploring, as I demo PWA in my â€œWhatâ€™s New in PS 3â€ talk and got curious. Iâ€™m not sure what the Microsofties will say but this is what Iâ€™ve found out:
PWA is nothing more than a web application in IIS (with some awesome functionality).
If you have the right permissions, you can edit FormLayout.Master, line 79 with the following change: